Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 257,682	$ 206,875	$ 156,749
Unrealized gains (losses) on securities
Before tax	22,123	(28,932)	(13,176)
Tax effect	(7,706)	11,378	5,153
Net of tax	14,417	(17,554)	(8,023)
Reclassification of net gains included in net income
Before tax	45	7,645	323
Tax effect	(18)	(3,004)	(127)
Net of tax	27	4,641	196
Reclassification of amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale
Before tax	1,479	(17,386)	(128)
Tax effect	(585)	6,826	50
Net of tax	894	(10,560)	(78)
Net unrealized gains (losses) on securities	13,496	(11,635)	(8,141)
Unrealized gains on derivative instruments
Before tax	4,958	10,473	533
Tax effect	(1,959)	(4,115)	(209)
Net unrealized gains on derivative instruments	2,999	6,358	324
Foreign currency translation adjustment
Before tax	9,446	3,737	(24,001)
Tax effect	(2,448)	(1,080)	6,442
Net foreign currency translation adjustment	6,998	2,657	(17,559)
Total other comprehensive income (loss)	23,493	(2,620)	(25,376)
Comprehensive income	$ 281,175	$ 204,255	$ 131,373