OPERATING SEGMENT INFORMATION - Summary of Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 04, 2015	Feb. 05, 2014
REVENUES
Net premiums earned	$ 187,869	$ 183,595	$ 180,226	$ 176,918	$ 179,371	$ 179,448	$ 172,339	$ 169,003	$ 728,608	$ 700,161	$ 687,375
Net investment income	13,153	13,504	13,048	13,370	13,754	13,964	13,431	13,495	53,075	54,644	55,608
Net realized gains	11,283	9,252	2,710	11,400	14,207	7,534	4,802	13,286	34,645	39,829	32,182
Consolidated revenue									816,328	794,634	775,165
INSURANCE EXPENSES
Loss and settlement expenses									349,778	299,045	296,609
Policy acquisition costs									249,612	241,078	229,283
Other insurance expenses									53,093	51,480	54,464
Insurance expenses									652,483	591,603	580,356
NET EARNINGS (LOSSES)
Net underwriting income									76,125	108,558	107,019
Net investment income	13,153	13,504	13,048	13,370	13,754	13,964	13,431	13,495	53,075	54,644	55,608
Net realized gains	11,283	9,252	2,710	11,400	14,207	7,534	4,802	13,286	34,645	39,829	32,182
General corporate expense and interest on debt									(17,596)	(17,263)	(17,660)
Equity in earnings of unconsolidated investees									10,833	10,914	12,338
Earnings before income taxes	38,006	31,142	42,341	45,593	45,582	51,937	54,650	44,513	157,082	196,682	189,487
Income tax expense									42,162	59,138	54,042
Net earnings	$ 32,187	$ 22,263	$ 29,077	$ 31,393	$ 33,853	$ 35,908	$ 37,185	$ 30,598	114,920	137,544	135,445
PARENT COMPANY
REVENUES
Net investment income									942	810	663
Net realized gains									(360)	139	271
NET EARNINGS (LOSSES)
Net investment income									942	810	663
Net realized gains									(360)	139	271
Equity in earnings of unconsolidated investees									9,764	9,893	12,009
Earnings before income taxes									(7,250)	(6,421)	(4,717)
Income tax expense									(8,467)	(5,499)	(7,959)
Net earnings									$ 114,920	137,544	135,445
Maui Jim Inc.
Segment reporting information
Ownership percentage	40.00%								40.00%
NET EARNINGS (LOSSES)
Equity in earnings of unconsolidated investees									$ 9,700	9,900	12,000
Prime Holdings Insurance Services, Inc. (Prime)
Segment reporting information
Ownership percentage	27.00%								27.00%			27.00%	20.00%
NET EARNINGS (LOSSES)
Equity in earnings of unconsolidated investees									$ 1,100	1,000	300
Casualty segment
REVENUES
Net premiums earned									454,843	412,248	382,105
INSURANCE EXPENSES
Loss and settlement expenses									259,907	218,414	199,133
Policy acquisition costs									128,566	119,529	108,747
Other insurance expenses									30,040	28,042	28,284
NET EARNINGS (LOSSES)
Net underwriting income									36,329	46,263	45,941
Property segment
REVENUES
Net premiums earned									152,167	170,924	197,776
INSURANCE EXPENSES
Loss and settlement expenses									71,350	69,851	89,589
Policy acquisition costs									54,167	57,214	58,646
Other insurance expenses									13,819	14,834	16,623
NET EARNINGS (LOSSES)
Net underwriting income									12,832	29,025	32,918
Property segment | Property reinsurance
Segment reporting information
Premiums Written, Gross									11,200	12,800	13,100
REVENUES
Net premiums earned									10,953	12,330	12,756
Property segment | Recreational Vehicle
Segment reporting information
Premiums Written, Gross									10,400	13,400	16,100
Surety segment
REVENUES
Net premiums earned									121,598	116,989	107,494
INSURANCE EXPENSES
Loss and settlement expenses									18,521	10,780	7,887
Policy acquisition costs									66,879	64,335	61,890
Other insurance expenses									9,234	8,604	9,557
NET EARNINGS (LOSSES)
Net underwriting income									$ 26,964	$ 33,270	$ 28,160