Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets [Roll Forward]
Total goodwill, beginning of period			$ 382,762
Total goodwill, end of period	$ 382,762	$ 382,537	382,762	$ 382,537
CDI current period amortization	(1,483)	(1,718)	(3,066)	(3,535)
Indefinite-Lived Intangible Assets (Excluding Goodwill)	919	919	919	919
Other intangible assets, net	20,511	26,924	20,511	26,924		$ 23,577
Total goodwill and intangible assets, end of period	403,273	409,461	$ 403,273	409,461
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	$ 58,598	$ 58,598
Accumulated amortization at beginning of period					$ (37,523)	$ (35,940)	$ (30,875)	$ (29,058)
Core deposit intangible, net, beginning of period	21,075	27,723	$ 22,658	29,540
CDI current period amortization	(1,483)	(1,718)	(3,066)	(3,535)
Total core deposit intangible, end of period	$ 19,592	$ 26,005	$ 19,592	$ 26,005