Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 14,853	$ 8,019	$ 28,450	$ 15,590
Securities:
Net change in unrealized holding gains (losses) on securities	1,206	(7,019)	3,990	(6,873)
Reclassification adjustment for losses realized in net income	0	0	0	71
Amortization of unrealized holding losses on securities transferred to the held to maturity category	(39)	(54)	(83)	(120)
Total securities	1,167	(7,073)	3,907	(6,922)
Derivative instruments:
Net change in unrealized holding (losses) gains on derivative instruments	(396)	992	(815)	1,199
Reclassification adjustment for gains realized in net income	0	(51)	0	(104)
Totals derivative instruments	(396)	941	(815)	1,095
Defined benefit pension and post-retirement benefit plans:
Net gain arising during the period	0	0	0	0
Less amortization of net actuarial loss recognized in net periodic pension cost	45	85	90	157
Total defined benefit pension and post-retirement benefit plans	45	85	90	157
Other comprehensive income (loss), net of tax	816	(6,047)	3,182	(5,670)
Comprehensive income	$ 15,669	$ 1,972	$ 31,632	$ 9,920