Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Changes in accumulated other comprehensive income by component
Balance, beginning of period	$ (18,517)	$ (33,725)	$ (15,346)
Other comprehensive income (loss)	(15,289)	17,562	(19,541)
Amounts reclassified from accumulated other comprehensive income (loss)	668	1,038	1,162
Total other comprehensive income (loss), net of tax	(14,621)	18,600	(18,379)
Balance, end of period	(33,138)	(18,517)	(33,725)
Accounting Standards Update 2018-02
Changes in accumulated other comprehensive income by component
Adoption impact of ASU 2018-02		(3,392)
Net Unrealized Gains (Losses) on Debt Securities Available for Sale and Interest-Only Strips
Changes in accumulated other comprehensive income by component
Balance, beginning of period	(16,353)	(28,601)	(9,707)
Other comprehensive income (loss)	(12,371)	15,387	(20,085)
Amounts reclassified from accumulated other comprehensive income (loss)	702	1,067	1,191
Total other comprehensive income (loss), net of tax	(11,669)	16,454	(18,894)
Balance, end of period	(28,022)	(16,353)	(28,601)
Net Unrealized Gains (Losses) on Debt Securities Available for Sale and Interest-Only Strips | Accounting Standards Update 2018-02
Changes in accumulated other comprehensive income by component
Adoption impact of ASU 2018-02		(4,206)
Net Unrealized Gains (Losses) on Net Investment Hedges
Changes in accumulated other comprehensive income by component
Balance, beginning of period	4,536	6,493	7,249
Other comprehensive income (loss)	10,450	(2,746)	(756)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Total other comprehensive income (loss), net of tax	10,450	(2,746)	(756)
Balance, end of period	14,986	4,536	6,493
Net Unrealized Gains (Losses) on Net Investment Hedges | Accounting Standards Update 2018-02
Changes in accumulated other comprehensive income by component
Adoption impact of ASU 2018-02		789
Foreign Currency Translation Adjustment
Changes in accumulated other comprehensive income by component
Balance, beginning of period	(6,843)	(11,764)	(13,064)
Other comprehensive income (loss)	(13,368)	4,921	1,300
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Total other comprehensive income (loss), net of tax	(13,368)	4,921	1,300
Balance, end of period	(20,211)	(6,843)	(11,764)
Foreign Currency Translation Adjustment | Accounting Standards Update 2018-02
Changes in accumulated other comprehensive income by component
Adoption impact of ASU 2018-02		0
Recognized Postretirement Prior Service Cost
Changes in accumulated other comprehensive income by component
Balance, beginning of period	143	147	176
Other comprehensive income (loss)	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	(34)	(29)	(29)
Total other comprehensive income (loss), net of tax	(34)	(29)	(29)
Balance, end of period	$ 109	143	$ 147
Recognized Postretirement Prior Service Cost | Accounting Standards Update 2018-02
Changes in accumulated other comprehensive income by component
Adoption impact of ASU 2018-02		$ 25