Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2010	$ 1,984,802	$ 259,931	$ 0	$ 1,301,042	$ 481,964	$ (58,135)
Balance, shares at Dec. 31, 2010		129,965,635,000
Comprehensive income:
Net income	35,776				35,776
Change in unrealized gain on securities available for sale, net of taxes and reclassification adjustment	40,922					40,922
Non-credit related unrealized loss on other-than-temporarily impaired debt securities, net of taxes	(1,393)					(1,393)
Change in unrealized loss on cash flow hedges, net of taxes	(15,286)					(15,286)
Adjustment to postretirement benefit obligations, net of taxes	(301)					(301)
Total comprehensive income	59,718
Issuance of common stock and options under employee benefit plans (Shares)		149,945,000
Issuance of common stock and options under employee benefit plans	3,134	300		2,834
Treasury stock purchased	(39)		(39)
Redemption of warrant	(5,269)			(5,269)
Cash dividends paid on common stock	(6,501)				(6,501)
Balance at Sep. 30, 2011	2,035,845	260,231	(39)	1,298,607	511,239	(34,193)
Balance, shares at Sep. 30, 2011		130,115,580,000
Balance at Dec. 31, 2011	2,189,628	314,136	(1,263)	1,397,152	525,657	(46,054)
Balance, shares at Dec. 31, 2011	157,067,887	157,067,887,000
Comprehensive income:
Net income	97,998				97,998
Change in unrealized gain on securities available for sale, net of taxes and reclassification adjustment	17,403					17,403
Non-credit related unrealized loss on other-than-temporarily impaired debt securities, net of taxes	1,425					1,425
Change in unrealized loss on cash flow hedges, net of taxes	(4,139)					(4,139)
Adjustment to postretirement benefit obligations, net of taxes	0
Total comprehensive income	112,687
Issuance of common stock in Tower Bancorp, Inc. purchase	302,112	61,522		240,590
Issuance of common stock in Tower Bancorp, Inc. purchase (Shares)		30,760,933,000
Retirement of common stock related to acquired employee benefit plans	0	(3,723)		3,723
Retirement of common stock related to acquired employee benefit plans (Shares)		(1,861,580,000)
Issuance of common stock and options under employee benefit plans (Shares)		709,012,000
Issuance of common stock and options under employee benefit plans	5,644	1,417		4,227
Treasury stock purchased	(105)		(105)
Cash dividends paid on common stock	(25,284)				(25,284)
Balance at Sep. 30, 2012	$ 2,584,682	$ 373,352	$ (1,368)	$ 1,645,692	$ 598,371	$ (31,365)
Balance, shares at Sep. 30, 2012	186,676,252	186,676,252,000