Shareholders' Equity, Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 364,316	$ 356,082
Other comprehensive income (loss)	(21,548)	8,763
Ending balance	305,383	366,070
Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	9,369	(7,347)
Other comprehensive income (loss) before reclassifications	(20,943)	7,978
Amounts reclassified from accumulated other comprehensive income (loss)	(605)	785
Other comprehensive income (loss)	(21,548)	8,763
Ending balance	(12,179)	1,416
Foreign Currency [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(494)	(1,139)
Other comprehensive income (loss) before reclassifications	(687)	307
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive income (loss)	(687)	307
Ending balance	(1,181)	(832)
Unrealized Holding Gains (Losses) on Available-for-sale Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	9,863	(6,208)
Other comprehensive income (loss) before reclassifications	(20,256)	7,671
Amounts reclassified from accumulated other comprehensive income (loss)	(605)	785
Other comprehensive income (loss)	(20,861)	8,456
Ending balance	$ (10,998)	$ 2,248