CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 10,538		$ 9,960		$ 29,633		$ 26,364
Securities available for sale:
Changes in fair value in securities available for sale	(953)		(129)		1,476		(5,003)
Net losses (gains) on securities reclassified into earnings	0	[1]	0	[1]	0	[1]	393	[1]
Net change in fair value of securities available for sale	(953)		(129)		1,476		(4,610)
Reclassification adjustment for other-than-temporary impairment losses transferred into earnings	0		0		0	[2]	1,384	[2]
Cash flow hedges:
Change in fair value of cash flow hedges	1		(47)		(29)		(15)
Net cash flow hedge losses reclassified into earnings	92	[3]	91	[3]	277	[3]	331	[3]
Net change in fair value of cash flow hedges	93		44		248		316
Defined benefit plan obligation adjustment	81	[4]	11,440	[4]	250	[4]	12,069	[4]
Total other comprehensive (loss) income, net of tax	(779)		11,355		1,974		9,159
Total comprehensive income	$ 9,759		$ 21,315		$ 31,607		$ 35,523

[1] Reported as total other-than-temporary impairment losses on securities in the Consolidated Statements of Income.

[2] Reported as the portion of loss recognized in other comprehensive income in the Consolidated Statements of Income.

[3] Included in interest expense on junior subordinated debentures in the Consolidated Statements of Income.

[4] Included in salaries and employee benefits expense in the Consolidated Statements of Income.