Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Goodwill and Intangible Assets [Line Items]
Goodwill, Acquired During Period	$ 230,819	$ 0	$ 230,819	$ 0
Indefinite-Lived Intangible Assets (Excluding Goodwill)	913	0	913	0
Intangible Assets, Net (Excluding Goodwill)	29,170	17,896	29,170	17,896		15,721
Goodwill and Intangible Assets [Roll Forward]
Total goodwill, beginning of period	115,554	115,554	115,554	115,554
Total goodwill, end of period	346,373	115,554	346,373	115,554
CDI current period amortization	(1,693)	(1,119)	(2,722)	(2,269)
Total goodwill and intangible assets, end of period	375,543	133,450	375,543	133,450
Core Deposits [Member]
Goodwill and Intangible Assets [Line Items]
Finite Lived Intangible Assets Acquired During the Period	15,257	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					32,441	32,441	32,441	32,441
Accumulated amortization at beginning of period					(17,748)	(16,720)	(13,425)	(12,275)
Core deposit intangible, net, beginning of period	14,693	19,016	15,721	20,166
CDI current period amortization	(1,693)	(1,120)	(2,721)	(2,270)
Total core deposit intangible, end of period	$ 28,257	$ 17,896	$ 28,257	$ 17,896