Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Goodwill and Intangible Assets [Line Items]
Goodwill, Acquired During Period	$ 0	$ 0	$ 229,677	$ 0
Indefinite-Lived Intangible Assets (Excluding Goodwill)	919	0	919	0
Intangible Assets, Net (Excluding Goodwill)	27,509	16,803	27,509	16,803		15,721
Goodwill and Intangible Assets [Roll Forward]
Total goodwill, beginning of period	345,231	115,554	115,554	115,554
Total goodwill, end of period	345,231	115,554	345,231	115,554
CDI current period amortization	(1,666)	(1,093)	(4,388)	(3,362)
Total goodwill and intangible assets, end of period	372,740	132,357	372,740	132,357
Core Deposits [Member]
Goodwill and Intangible Assets [Line Items]
Finite Lived Intangible Assets Acquired During the Period	0	0	15,257	0
Estimated life of CDI, in years			10 years
Goodwill and Intangible Assets [Roll Forward]
Gross core deposit intangible balance, beginning of period					47,698	32,441	32,441	32,441
Accumulated amortization at beginning of period					(19,441)	(16,720)	(14,545)	(12,275)
Core deposit intangible, net, beginning of period	28,257	17,896	15,721	20,166
CDI current period amortization	(1,667)	(1,093)	(4,388)	(3,363)
Total core deposit intangible, end of period	$ 26,590	$ 16,803	$ 26,590	$ 16,803