Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net earnings	$ 114,920	$ 137,544	$ 135,445
Adjustments to reconcile net earnings to net cash provided by operating activities
Net realized gains	(34,645)	(39,829)	(32,182)
Depreciation	6,430	5,406	4,557
Other items, net	17,699	15,006	10,818
Change in:
Accrued investment income	285	(249)	1,081
Premiums and reinsurance balances receivable (net of direct write-offs and commutations)	17,275	10,911	(2,064)
Reinsurance balances payable	(19,628)	(457)	(9,321)
Funds held	18,488	2,773	(10,175)
Ceded unearned premium	660	1,128	6,446
Reinsurance balances recoverable on unpaid losses	9,620	37,262	19,818
Deferred policy acquisition costs	(3,318)	(4,706)	(3,615)
Accrued expenses	(3,750)	(7,406)	3,552
Unpaid losses and settlement expenses	35,552	(17,255)	(8,393)
Unearned premiums	11,683	20,682	9,331
Income taxes
Current	12,573	7,069	(155)
Deferred	1,128	7,034	5,446
Stock option excess tax benefit	(9,576)	(11,413)	(1,766)
Changes in investment in unconsolidated investees:
Undistributed earnings	(10,833)	(10,914)	(12,338)
Dividends received	9,900		6,600
Net cash provided by operating activities	174,463	152,586	123,085
Purchase of:
Fixed income, available-for-sale	(557,067)	(665,422)	(470,210)
Equity securities, available-for-sale	(36,335)	(39,905)	(18,088)
Property and equipment	(16,155)	(10,035)	(7,121)
Investment in equity method investee		(1,711)	(5,301)
Acquisition of agency	(850)
Other	(7,722)	(4,642)	(5,534)
Proceeds from sale of:
Fixed income, held-to-maturity			654
Fixed income, available-for-sale	329,091	436,680	342,308
Equity securities, available-for-sale	89,909	53,110	72,869
Short-term investments, net	2,564	6,637	11,401
Property and equipment	1,688	76	276
Subsidiary (RLI Indemnity Company)		7,500
Other		135
Proceeds from call or maturity of:
Fixed income, available-for-sale	141,255	156,980	101,517
Net cash used in investing activities	(53,622)	(60,597)	22,771
Cash Flows from Financing Activities
Stock option excess tax benefit	9,576	11,413	1,766
Proceeds from stock option exercises	(741)	(3,364)	3,386
Cash dividends paid	(122,488)	(119,577)	(159,857)
Net cash used in financing activities	(113,653)	(111,528)	(154,705)
Net increase (decrease) in cash	7,188	(19,539)	(8,849)
Cash at the beginning of the period	11,081	30,620	39,469
Cash at the end of the period	$ 18,269	$ 11,081	$ 30,620