CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 15,104	$ 13,824
Other comprehensive (loss) income, net of tax
Unrealized gains (losses) on investment securities arising during the period	3,862	(3,357)
Change in retirement obligation	237	445
Unrealized gain (loss) on derivatives	(457)	126
Unrealized gain (loss) on foreign currency exchange	(9)	(12)
Other comprehensive income (loss)	3,633	(2,798)
Comprehensive income	$ 18,737	$ 11,026