Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 14,655		$ 11,601		$ 39,665		$ 32,658
Unrealized gains (losses) on securities
Change in fair value of securities available for sale	(148)		837		(5,517)		537
Less: net security losses reclassified into earnings	0		0		3		45
Net change in fair value of securities available for sale	(148)		837		(5,514)		582
Unrealized gains (losses) on cash flow hedges
Change in fair value of cash flow hedges	(411)		(929)		350		(2,125)
Less: net cash flow hedge losses reclassified into earnings	866	[1]	810	[1]	2,557	[1]	2,371	[1]
Net change in fair value of cash flow hedges	455		(119)		2,907		246
Amortization of certain costs included in net periodic retirement costs	30	[2]	23	[2]	73		69
Total other comprehensive (loss) income	337		741		(2,534)		897
Total comprehensive income	$ 14,992		$ 12,342		$ 37,131		$ 33,555

[1] Includes the remaining balance of a realized but unrecognized gain, net of tax, from the termination of interest rate swaps in June 2009. The original gain of $1.4 million, net of tax, is being recognized in earnings through December 2018, the original maturity date of the swap. The balance of this gain has amortized to $751,000 and $895,000 at September 30, 2013 and 2012, respectively.

[2] The amortization of prior service costs is included in the computation of net periodic pension cost as disclosed in the Employee Benefit Plans footnote in the Company's Annual Report on Form 10-K for the year ended December 31, 2012, filed with the Securities and Exchange Commission.