Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, except Share data	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, 2011	$ 2,189,628	$ 314,136	$ (1,263)	$ 1,397,152	$ 525,657	$ (46,054)
Balance, Shares at Dec. 31, 2011		157,067,887
Total comprehensive income	24,234				23,473	761
Issuance of common stock in Tower Bancorp, Inc. acquisition	301,405	61,522		239,883
Issuance of common stock in Tower Bancorp, Inc. acquisition (Shares)		30,760,933
Issuance of common stock and share-based awards under employee benefit plans (shares)		229,849
Issuance of common stock and share-based awards under employee benefit plans	1,986	459		1,527
Treasury stock purchased	(15)		(15)
Cash dividends paid on common stock	(4,654)				(4,654)
Balance at Mar. 31, 2012	2,512,584	376,117	(1,278)	1,638,562	544,476	(45,293)
Balance, Shares at Mar. 31, 2012		188,058,669
Balance at Dec. 31, 2012	2,595,909	373,623	(1,850)	1,645,958	615,436	(37,258)
Balance, Shares at Dec. 31, 2012		186,811,642
Total comprehensive income	41,002				42,399	(1,397)
Issuance of common stock and share-based awards under employee benefit plans (shares)		247,379
Issuance of common stock and share-based awards under employee benefit plans	2,599	495		2,104
Treasury stock purchased	(21)		(21)
Balance at Mar. 31, 2013	$ 2,639,489	$ 374,118	$ (1,871)	$ 1,648,062	$ 657,835	$ (38,655)
Balance, Shares at Mar. 31, 2013		187,059,021