Shareholders' Equity - AOCI Components (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	$ 37,857	$ 36,787	$ (2,234)	$ 89,773
Amounts reclassified from AOCI to net income, net of tax	(2,368)	(15,415)	(6,401)	(2,927)
Other comprehensive income (loss), after tax	35,489	21,372	(8,635)	86,846
Ending balance	530,739	590,572	530,739	590,572
Change in net unrealized gains on investment, attributable to parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(22,125)	1,714	21,996
Other comprehensive income (loss) before reclassifications	41,677	42,979	1,589
Amounts reclassified from AOCI to net income, net of tax	(2,368)	(15,415)	(6,401)
Other comprehensive income (loss), after tax	39,309	27,564	(4,812)
Ending balance	17,184	29,278	17,184	29,278
Foreign currency translation, attributable to parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(4,163)	(1,934)	(4,160)
Other comprehensive income (loss) before reclassifications	(3,820)	(6,192)	(3,823)
Amounts reclassified from AOCI to net income, net of tax	0	0	0
Other comprehensive income (loss), after tax	(3,820)	(6,192)	(3,823)
Ending balance	(7,983)	(8,126)	(7,983)	(8,126)
Change in net unrealized gains on investment, including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				(59,762)
Other comprehensive income (loss) before reclassifications				91,967
Amounts reclassified from AOCI to net income, net of tax				(2,927)
Other comprehensive income (loss), after tax				89,040
Ending balance		29,278		29,278
Foreign currency translation, including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				(5,932)
Other comprehensive income (loss) before reclassifications				(2,194)
Amounts reclassified from AOCI to net income, net of tax				0
Other comprehensive income (loss), after tax				(2,194)
Ending balance		(8,126)		(8,126)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(26,288)	(220)	17,836	(65,616)
Ending balance	$ 9,201	21,152	$ 9,201	21,152
AOCI Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				(65,694)
Ending balance		$ 21,152		$ 21,152