Acquisitions (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands		9 Months Ended
	Oct. 01, 2016	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Brokered deposits			$ 1,961,125	$ 1,378,983
Common stock, shares issued (in shares)			142,677,449	142,025,720
Assets acquired:
Goodwill			$ 57,315	$ 59,678
Liabilities assumed:
Fair value of common stock issued			142,678	142,026
Long-term debt			1,706,138	2,160,881
Other intangible assets			11,254	$ 13,223
Global One
Business Acquisition [Line Items]
Consideration transferred	$ 30,000
Common stock, shares issued (in shares)	821,000
Assets acquired:
Cash and due from banks	$ 9,554
Commercial and industrial loans	357,307
Goodwill	32,884
Other intangible assets	12,500		$ 12,500
Other assets	3,681
Total assets acquired	415,926
Liabilities assumed:
Notes payable	358,560
Earnout liability	12,234
Deferred tax liability, net	3,229
Other liabilities	11,903
Total liabilities assumed	385,926
Consideration paid	30,000
Cash paid	3,408
Adjustment in goodwill		$ 2,400
Fair value of common stock issued	26,592
Loans, unpaid principal balance	356,700
Long-term debt	$ 357,000
Adjustment in contingent consideration		$ 1,800