CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 19,814	$ 17,621
Other comprehensive (loss) income, net of tax
Unrealized gains (losses) on investment securities arising during the period	7,043	5,008
Change in retirement obligation	200	183
Unrealized gain (loss) on derivatives	128	(816)
Unrealized gain (loss) on foreign currency exchange	0	(20)
Other comprehensive income (loss)	7,371	4,355
Comprehensive income	$ 27,185	$ 21,976