Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 13,597	$ 7,571
Securities:
Unrealized holding gains on securities	2,784	146
Reclassification adjustment for losses (gains) realized in net income	0	71
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(44)	(66)
Total securities	2,740	151
Derivative instruments:
Unrealized holding (losses) gains on derivative instruments	(419)	207
Reclassification adjustment for gains realized in net income	0	(53)
Totals derivative instruments	(419)	154
Defined benefit pension and post-retirement benefit plans:
Net (loss) gain arising during the period	0	0
Less amortization of net actuarial loss recognized in net periodic pension cost	45	72
Total defined benefit pension and post-retirement benefit plans	45	72
Other comprehensive income, net of tax	2,366	377
Comprehensive income	$ 15,963	$ 7,948