Shareholders' Equity (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	$ 2,352,274	$ 2,069,822	$ 1,900,589
Total other comprehensive (loss) income	(2,620)	(25,376)	25,704
Balance at end of period	2,695,617	2,352,274	2,069,822
Accumulated Unrealized Losses on Securities
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(17,674)	(9,533)	(53,665)
Other comprehensive income (loss) during the period, net of tax, before reclassification	(17,554)	(8,023)	43,828
Amount reclassified from accumulated other comprehensive income (loss), net of tax	(4,641)	(196)	304
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale	10,560	78
Total other comprehensive (loss) income	(11,635)	(8,141)	44,132
Balance at end of period	(29,309)	(17,674)	(9,533)
Accumulated Unrealized Losses on Derivative Instruments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(2,193)	(2,517)	(2,462)
Other comprehensive income (loss) during the period, net of tax, before reclassification	4,464	(941)	(1,244)
Amount reclassified from accumulated other comprehensive income (loss), net of tax	1,894	1,265	1,189
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale	0	0
Total other comprehensive (loss) income	6,358	324	(55)
Balance at end of period	4,165	(2,193)	(2,517)
Accumulated Foreign Currency Translation Adjustments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(42,841)	(25,282)	(6,909)
Other comprehensive income (loss) during the period, net of tax, before reclassification	2,657	(17,559)	(18,373)
Amount reclassified from accumulated other comprehensive income (loss), net of tax	0	0	0
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale	0	0
Total other comprehensive (loss) income	2,657	(17,559)	(18,373)
Balance at end of period	(40,184)	(42,841)	(25,282)
AOCI Attributable to Parent
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(62,708)	(37,332)	(63,036)
Other comprehensive income (loss) during the period, net of tax, before reclassification	(10,433)	(26,523)	24,211
Amount reclassified from accumulated other comprehensive income (loss), net of tax	(2,747)	1,069	1,493
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale	10,560	78
Total other comprehensive (loss) income	(2,620)	(25,376)	25,704
Balance at end of period	$ (65,328)	$ (62,708)	$ (37,332)