Schedule II - Condensed Statements of Comprehensive Income (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net change in unrealized gains on securities, taxes	$ 158,653	$ (135,743)	$ 231,472
Net change in other-than-temporary impairment gains recognized in other comprehensive income, taxes	(2,240)	90	1,382
Net change in foreign currency translation, taxes	5,100	2,745	8,162
Amortization of pension and postretirement unrecognized net periodic benefit cost, taxes	(4,091)	26,534	(51,302)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net change in unrealized gains on securities, taxes	8,797	(3,273)	1,863
Net change in foreign currency translation, taxes	(45)	(68)	32
Amortization of pension and postretirement unrecognized net periodic benefit cost, taxes	$ (4,082)	$ 26,516	$ (51,301)