Investments (Balance of and Changes in AOCI Components) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			$ 178,691
Income tax benefit (expense)	$ 21,601	$ (3,146)	(13,451)	$ (121,184)
Balance	109,324		109,324		$ 178,691
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			(67)	403	403
Change in other comprehensive income (loss) before reclassifications			(391)	(482)
Amounts reclassified from AOCI			0	0
Income tax benefit (expense)			137	169
Balance	(321)	90	(321)	90	(67)	$ 403
Total net unrealized investment gains (losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			178,758	56,243	56,243
Change in other comprehensive income (loss) before reclassifications			(97,212)	134,399
Amounts reclassified from AOCI	(5,071)		(9,115)	(16,233)
Income tax benefit (expense)			37,214	(41,358)
Balance	109,645	133,051	109,645	133,051	178,758	56,243
Cash Flow Hedge Gain (Loss) To AOCI			40,000	(6,000)	12,000	(5,000)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance			178,691	56,646	56,646
Change in other comprehensive income (loss) before reclassifications			(97,603)	133,917
Amounts reclassified from AOCI	(5,071)		(9,115)	(16,233)
Income tax benefit (expense)			37,351	(41,189)
Balance	$ 109,324	$ 133,141	$ 109,324	$ 133,141	$ 178,691	$ 56,646