Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 4,613	$ 2,112	$ 4,083	$ 2,167
Total realized/unrealized gains (losses):
Included in other comprehensive income	3,519		3,519
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	3,091	7
Sales	(136)	(157)	(2,697)	(219)
Balance at end of period	4,613	2,112	4,083	2,167	$ 7,996	$ 1,955
Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	1,192	1,791	1,228	1,846
Total realized/unrealized gains (losses):
Included in other comprehensive income	0		0
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	0	7
Sales	(136)	(157)	(172)	(219)
Balance at end of period	1,192	1,791	1,228	1,846	1,056	1,634
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	3,421	321	2,855	321
Total realized/unrealized gains (losses):
Included in other comprehensive income	3,519		3,519
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	3,091	0
Sales	0	0	(2,525)	0
Balance at end of period	3,421	321	2,855	321	6,940	321
Real Estate Acquired
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	12,849	10,897	12,149	12,658
Total realized/unrealized gains (losses):
Included in other comprehensive income	0		0
Included in earnings and reported as losses incurred, net	651	31	358	(472)
Purchases	6,748	5,917	19,015	16,714
Sales	(10,606)	(8,850)	(21,880)	(20,905)
Balance at end of period	$ 12,849	$ 10,897	$ 12,149	$ 12,658	$ 9,642	$ 7,995