Summary of Significant Accounting Policies (Details 9) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrealized Gains and Losses on Fixed Maturities and Equity Securities
Beginning balance	[1],[2]	$ 175,167	$ 297,554	$ 133,990
Other comprehensive income (loss) before reclassifications	[1],[2]	3,935	(114,803)	170,677
Amounts reclassified from accumulated other comprehensive income (loss)	[1],[2]	(3,364)	(7,584)	(7,113)
Net current period other comprehensive income (loss)	[1],[2]	571	(122,387)	163,564
Ending balance	[1],[2]	175,738	175,167	297,554
Defined Benefit Plans
Beginning balance	[1]	(11,794)	(12,953)	(11,776)
Other comprehensive income (loss) before reclassifications	[1]	(23)	1,159	(1,177)
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	0	0	0
Change in net funded status of benefit plans	[1]	(23)	1,159	(1,177)
Ending balance	[1]	(11,817)	(11,794)	(12,953)
Beginning balance	[1]	163,373	284,601	122,214
Other comprehensive income (loss) before reclassifications	[1]	3,912	(113,644)	169,500
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	(3,364)	(7,584)	(7,113)
Net current period other comprehensive income (loss)	[1]	548	(121,228)	162,387
Ending balance	[1]	$ 163,921	$ 163,373	$ 284,601

[1] All amounts are net of tax.

[2] The pretax amounts reclassified from accumulated other comprehensive income, $5,176, $11,667 and $10,943, are included in net realized investment gains and losses and the related tax expenses, $1,812, $4,083 and $3,830, are included in income tax expense in the Consolidated Statements of Operations for the years ended December 31, 2016, 2015 and 2014, respectively.