Derivative Financial Instruments Derivative Financial Instruments (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Aggregate fair value of derivatives	$ 38,324,000	$ 76,107,000
Pledged collateral	0	45,940,000
Fair value of assets needed for settlement	38,324,000
Unrestricted cash collateral under derivative counterparty	0	50,924,000
Collateral under derivative counterparty to satisfy netting agreements	103,214,000	19,060,000
Net derivative gains	9,581,000
Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value	(5,545,000)	11,257,000
Policyholders' Funds
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives - GLWB	5,712,000	11,257,000
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Average notional amount of the derivative instruments	784,900,000	443,589,000
Cross-currency swaps
Derivative Instruments, Gain (Loss) [Line Items]
Average notional amount of the derivative instruments	1,141,967,000	937,242,000
Futures
Derivative Instruments, Gain (Loss) [Line Items]
Average notional amount of the derivative instruments	145,658,000	111,801,000
Swaptions
Derivative Instruments, Gain (Loss) [Line Items]
Average notional amount of the derivative instruments	156,632,000	212,299,000
Other forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Average notional amount of the derivative instruments	$ 2,230,167,000	$ 5,014,845,000