Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill and Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	$ 919	$ 919	$ 919
Intangible Assets, Net (Excluding Goodwill)	23,577	30,459	25,852
Goodwill and Intangible Assets [Roll Forward]
Total goodwill, beginning of period	382,537	343,952	115,554
Established through acquisitions	225	38,585	228,398
Total goodwill, end of period	382,762	382,537	343,952
Core deposit intangible, net, beginning of period	30,459
CDI current period amortization	(6,882)	(6,293)	(6,045)
Total core deposit intangible, end of period	23,577	30,459
Total goodwill and intangible assets, end of period	406,339	412,996	369,804
Core Deposits [Member]
Goodwill and Intangible Assets [Roll Forward]
Gross core deposit intangible balance, beginning of period	58,598	47,698	32,441
Accumulated amortization, beginning of period	(29,058)	(22,765)	(16,720)
Core deposit intangible, net, beginning of period	29,540	24,933	15,721
Established through acquisitions	0	10,900	15,257
CDI current period amortization	(6,882)	(6,293)	(6,045)
Total core deposit intangible, end of period	$ 22,658	$ 29,540	$ 24,933
Estimated life of CDI, in years	10 years