| Component: (Network and Table) | |
|---|---|
| Network | 00500 - Statement - Consolidated Statements of Cash Flows (http://www.safetyinsurance.com/role/StatementConsolidatedStatementsOfCashFlows)  | 
| Table | (Implied) | 
| Reporting Entity [Axis] | 0001172052 (http://www.sec.gov/CIK) | 
| Consolidated Statements of Cash Flows | Period [Axis] | ||
|---|---|---|---|
2016-01-01 - 2016-12-31  | 2015-01-01 - 2015-12-31  | 2014-01-01 - 2014-12-31  | |
Consolidated Statements of Cash Flows  | |||
Cash flows from operating activities:  | |||
Net income (loss)  | 64,585,000    | (13,853,000)   | 59,354,000    | 
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:  | |||
Depreciation and amortization, net  | |||
Provision (credit) for deferred income taxes  | (  | ||
Net realized (gains) losses on investments  | (5,559,000)   | 469,000    | (197,000)   | 
Net impairment losses on investments  | 798,000    | 796,000    | |
Earnings from partnership investments  | (3,185,000)   | (2,387,000)   | (878,000)   | 
Changes in assets and liabilities:  | |||
Accounts receivable  | (  | (  | (  | 
Accrued investment income  | |||
Receivable from reinsurers  | (  | (  | (  | 
Ceded unearned premiums  | (  | (  | (  | 
Deferred policy acquisition costs  | (  | (  | (  | 
Taxes recoverable  | (  | ||
Other assets  | (  | (  | |
Loss and loss adjustment expense reserves  | |||
Unearned premium reserves  | |||
Accounts payable and accrued liabilities  | (  | (  | |
Payable to reinsurers  | |||
Other liabilities  | (  | (  | |
Net cash provided by operating activities  | |||
Cash flows from investing activities:  | |||
Fixed maturities purchased  | (  | (  | (  | 
Equity securities purchased  | (  | (  | (  | 
Other invested assets purchased  | (  | (  | (  | 
Proceeds from sales and paydowns of fixed maturities  | |||
Proceeds from maturities, redemptions, and calls of fixed maturities  | |||
Proceed from sales of equity securities  | |||
Proceeds from other invested assets redeemed  | |||
Fixed assets purchased  | (  | (  | (  | 
Net cash (used for) provided by investing activities  | (  | (  | |
Cash flows from financing activities:  | |||
Proceeds from stock options exercised  | |||
Excess tax (expense) benefit from stock options exercised  | (  | ||
Dividends paid to shareholders  | (  | (  | (  | 
Acquisition of treasury stock  | (  | ||
Net cash used for financing activities  | (  | (  | (  | 
Net increase in cash and cash equivalents  | (  | (  | |
Cash and cash equivalents at beginning of year  | 47,494,000    | ||
Cash and cash equivalents at end of year  | 20,052,000    | 47,494,000    | 42,455,000    | 
Supplemental disclosure of cash flow information:  | |||
Federal and state income taxes  | |||
Interest  | |||