Certain Nontraditional Long-Duration Contracts (Changes in Deferred Sales Inducements, Reported as "Interest credited to policyholders' account (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
deferredsalesinducements
Deferred Sales Inducements, Beginning Balance	$ 809,247	$ 556,830	$ 445,841
deferredsalesinducementsadditions	11,515	31,370	59,269
Amortization - Impact of assumption and experience unlocking and true-ups	45,417	13,038	133,214
Amortization - All other	(204,563)	179,219	(94,752)
Change in unrealized investment gains and losses	3,591	28,790	13,258
Deferred Sales Inducements, Ending Balance	$ 665,207	$ 809,247	$ 556,830