Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Goodwill and Intangible Assets [Line Items]
Goodwill, Purchase Accounting Adjustments	$ 225	$ 0	$ 225	$ 0
Goodwill and Intangible Assets [Roll Forward]
Total goodwill, beginning of period		343,952	382,537	343,952
Total goodwill, end of period	382,762	343,952	382,762	343,952
CDI current period amortization	(1,695)	(1,456)	(5,230)	(4,516)
Indefinite-Lived Intangible Assets (Excluding Goodwill)	919	919	919	919
Other intangible assets, net	25,229	21,336	25,229	21,336		$ 30,459
Total goodwill and intangible assets, end of period	407,991	365,288	$ 407,991	365,288
Core Deposits [Member]
Goodwill and Intangible Assets [Line Items]
Estimated life of CDI, in years			10 years
Goodwill and Intangible Assets [Roll Forward]
Gross core deposit intangible balance, beginning of period					$ 58,598	58,598	$ 47,698	$ 47,698
Accumulated amortization at beginning of period					$ (32,593)	$ (29,058)	$ (25,825)	$ (22,765)
Core deposit intangible, net, beginning of period	26,005	21,873	$ 29,540	24,933
CDI current period amortization	(1,695)	(1,456)	(5,230)	(4,516)
Total core deposit intangible, end of period	$ 24,310	$ 20,417	$ 24,310	$ 20,417