Investments (Net Unrealized Gains Losses on Investments by Asset Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) on investments	$ 154,502	$ 198,923
Derivatives designated as cash flow hedges
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) on investments	10,075	4,839
Fixed maturities
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) on investments	141,964	191,339
Fixed maturities | Securities Related to Other Than Temporary Impairments
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) on investments	17	1
Equity securities, available-for-sale
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) on investments	3	3
Affiliated notes
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) on investments	2,026	2,351
Other investments
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) on investments	$ 417	$ 390