Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (314,948)
Amounts reclassified from AOCI	(3,013)	$ (2,146)
Income tax benefit (expense)	(117,370)	85,830
Ending balance	(279,616)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(78)	(65)
Change in OCI before reclassifications	11	28
Amounts reclassified from AOCI	0	0
Income tax benefit (expense)	(4)	(10)
Ending balance	(71)	(47)
Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(314,870)	46,231
Change in OCI before reclassifications	51,334	25,501
Amounts reclassified from AOCI	3,013	2,146
Income tax benefit (expense)	(19,022)	(9,676)
Ending balance	(279,545)	64,202
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(314,948)	46,166
Change in OCI before reclassifications	51,345	25,529
Amounts reclassified from AOCI	3,013	2,146
Income tax benefit (expense)	(19,026)	(9,686)
Ending balance	(279,616)	64,155
Cash flow hedges | Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	12,000	15,000
Ending balance	$ 6,000	$ 11,000