Investments (Changes in Net Unrealized Gains/Losses on Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investment Holdings [Line Items]
Fixed maturity securities held for investment carried at amortized cost	$ (10,651)	$ 14,821	$ (848)
Investments carried at fair value	(1,642,010)	2,157,460	(2,140,941)
Adjustment for effect on other balance sheet accounts:
Deferred policy acquisition costs and deferred sales inducements	842,412	(1,118,683)	1,155,386
Deferred income tax asset/liability	279,860	(363,572)	344,944
Total adjustment for effect on other balance sheet accounts	1,122,272	(1,482,255)	1,500,330
Change in net unrealized gains on investments carried at fair value	(519,738)	675,205	(640,611)
Fixed Maturity Securities [Member]
Investment Holdings [Line Items]
Investments carried at fair value	(1,642,027)	2,157,439	(2,132,392)
Equity Securities [Member]
Investment Holdings [Line Items]
Investments carried at fair value	$ 17	$ 21	$ (8,549)