Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period			$ 55,568
Other comprehensive income	$ 63,844	$ 49,163	77,748	$ 123,971
End of period	133,302		133,302
Net realized investment gains	40,453	6,315	92,801	31,772
Income before income taxes	160,961	158,314	345,258	332,990
Tax effect	(51,388)	(49,408)	(111,011)	(103,837)
Net income before noncontrolling interests	109,573	108,906	234,247	229,153
Net change in period	20,247	(55,870)	42,982	(57,917)
Other comprehensive income (loss), pre-tax	88,529		101,693
Other comprehensive income (loss), tax effect	(24,685)		(23,945)
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	69,491	8,124	55,568	(66,698)
Other comprehensive income before reclassifications	89,562	57,679	132,291	133,874
Amounts reclassified from AOCI	(25,718)	(8,516)	(54,543)	(9,903)
Other comprehensive income	63,844	49,163	77,748	123,971
Unrealized investment gain related to non-controlling interest	(33)	(5)	(14)	9
End of period	133,302	57,282	133,302	57,282
Other comprehensive income (loss), pre-tax		100,735		213,078
Other comprehensive income (loss), tax effect		(51,572)		(89,107)
Accumulated Other Comprehensive Income | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	(39,566)	(13,101)	(83,912)	(15,235)
Tax effect	13,848	4,585	29,369	5,332
Net income before noncontrolling interests	(25,718)	(8,516)	(54,543)	(9,903)
Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	418,342	257,564	427,154	180,695
Other comprehensive income before reclassifications	69,315	113,549	89,309	191,791
Amounts reclassified from AOCI	(25,718)	(8,516)	(54,543)	(9,903)
Other comprehensive income	43,597	105,033	34,766	181,888
Unrealized investment gain related to non-controlling interest	(33)	(5)	(14)	9
End of period	461,906	362,592	461,906	362,592
Unrealized investment gains, pre-tax	68,282	156,605	58,711	270,995
Unrealized investment gains, tax effect	(24,685)	(51,572)	(23,945)	(89,107)
Unrealized investment gains, after-tax amounts	43,597	105,033	34,766	181,888
Unrealized Investment Gains (Losses) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized investment gains	(39,566)	(13,101)	(83,912)	(15,235)
Tax effect	13,848	4,585	29,369	5,332
Net income before noncontrolling interests	(25,718)	(8,516)	(54,543)	(9,903)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(348,851)	(249,440)	(371,586)	(247,393)
Other comprehensive income before reclassifications	20,247	(55,870)	42,982	(57,917)
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive income	20,247	(55,870)	42,982	(57,917)
Unrealized investment gain related to non-controlling interest	0	0	0	0
End of period	(328,604)	(305,310)	(328,604)	(305,310)
Currency translation adjustment, pre-tax	20,247	(55,870)	42,982	(57,917)
Currency translation adjustment, tax effect	0	0	0	0
Net change in period	20,247	(55,870)	42,982	(57,917)
Currency Translation Adjustments | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	0	0	0	0
Tax effect	0	0	0	0
Net income before noncontrolling interests	$ 0	$ 0	$ 0	$ 0