Shareholders' Equity - AOCI Components (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	$ 7,998	$ 9,339	$ 5,764	$ 99,112
Amounts reclassified from AOCI to net income, net of tax	(3,242)	(8,555)	(9,643)	(11,482)
Other comprehensive income (loss), after tax	4,756	784	(3,879)	87,630
Ending balance	538,086	533,155	538,086	533,155
Change in net unrealized gains on investment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	17,184	29,278	21,996
Other comprehensive income (loss) before reclassifications	14,996	(2,141)	16,585
Amounts reclassified from AOCI to net income, net of tax	(3,242)	(8,555)	(9,643)
Other comprehensive income (loss), after tax	11,754	(10,696)	6,942
Ending balance	28,938	18,582	28,938	18,582
Foreign currency translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(7,983)	(8,126)	(4,160)
Other comprehensive income (loss) before reclassifications	(6,998)	11,480	(10,821)
Amounts reclassified from AOCI to net income, net of tax	0	0	0
Other comprehensive income (loss), after tax	(6,998)	11,480	(10,821)
Ending balance	(14,981)	3,354	(14,981)	3,354
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				89,826
Amounts reclassified from AOCI to net income, net of tax				(11,482)
Other comprehensive income (loss), after tax				78,344
Ending balance		18,582		18,582
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				9,286
Amounts reclassified from AOCI to net income, net of tax				0
Other comprehensive income (loss), after tax				9,286
Ending balance		3,354		3,354
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	9,201	21,152	17,836	(65,616)
Ending balance	$ 13,957	21,936	$ 13,957	21,936
AOCI Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				(65,694)
Ending balance		$ 21,936		$ 21,936