Investments (All Other Net Unrealized Investment Gains and Losses in AOCI) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Balance	$ 84,622	$ 70,867
Other Net Unrealized Investment Gains and Losses [Member] | Accumulated Net Unrealized Investment Gain (Loss) Pre Tax [Member]
Balance	184,727	376,777		441,677
Net investment gains (losses) on investments arising during the period	28,590	(183,950)		(42,295)
Reclassification adjustment for (gains) losses included in net income	(14,395)	(8,100)		(22,605)
Reclassification adjustment for OTTI losses excluded from net income		0	[1]	0	[1]
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs	0	0		0
Impact of net unrealized investment (gains) losses on policyholders' account balance	0	0		0
Balance	198,922	184,727		376,777
Other Net Unrealized Investment Gains and Losses [Member] | Deferred Costs Policy Acquisition And Sales Inducements And Valuation Of Business Acquired, Pre Tax [Member]
Balance	(66,452)	(147,089)		(192,119)
Net investment gains (losses) on investments arising during the period	0	0		0
Reclassification adjustment for (gains) losses included in net income	0	0		0
Reclassification adjustment for OTTI losses excluded from net income		0	[1]	0	[1]
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs	7,407	80,637		45,030
Impact of net unrealized investment (gains) losses on policyholders' account balance	0	0		0
Balance	(59,045)	(66,452)		(147,089)
Other Net Unrealized Investment Gains and Losses [Member] | Policyholders Account Balances Pre Tax [Member]
Balance	(8,187)	(2,164)		0
Net investment gains (losses) on investments arising during the period	0	0		0
Reclassification adjustment for (gains) losses included in net income	0	0		0
Reclassification adjustment for OTTI losses excluded from net income		0	[1]	0	[1]
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs	0	0		0
Impact of net unrealized investment (gains) losses on policyholders' account balance	(185)	(6,023)		(2,164)
Balance	(8,372)	(8,187)		(2,164)
Other Net Unrealized Investment Gains and Losses [Member] | Deferred Income Tax Liability Benefit [Member]
Balance	(39,363)	(80,468)		(88,181)
Net investment gains (losses) on investments arising during the period	(10,013)	64,383		14,804
Reclassification adjustment for (gains) losses included in net income	5,036	2,835		7,912
Reclassification adjustment for OTTI losses excluded from net income		0	[1]	0	[1]
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs	(2,594)	(28,222)		(15,760)
Impact of net unrealized investment (gains) losses on policyholders' account balance	64	2,109		757
Balance	(46,870)	(39,363)		(80,468)
Other Net Unrealized Investment Gains and Losses [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Balance	70,725	147,056		161,377
Net investment gains (losses) on investments arising during the period	18,577	(119,567)		(27,491)
Reclassification adjustment for (gains) losses included in net income	(9,359)	(5,265)		(14,693)
Reclassification adjustment for OTTI losses excluded from net income		0	[1]	0	[1]
Impact of net unrealized investment (gains) losses on deferred policy acquisition costs	4,813	52,415		29,270
Impact of net unrealized investment (gains) losses on policyholders' account balance	(121)	(3,914)		(1,407)
Balance	$ 84,635	$ 70,725		$ 147,056

[1] Includes cash flow hedges. See Note 11 for information on cash flow hedges.