Parent Company Financial Information (Condensed Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Proceeds from Warrant Exercises	$ 5,000us-gaap_ProceedsFromWarrantExercises	$ 0us-gaap_ProceedsFromWarrantExercises	$ 0us-gaap_ProceedsFromWarrantExercises
Operating Activities
Net Income (Loss)	81,574us-gaap_NetIncomeLoss	60,016us-gaap_NetIncomeLoss	46,143us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	2,859us-gaap_ShareBasedCompensation	2,844us-gaap_ShareBasedCompensation	1,622us-gaap_ShareBasedCompensation
Net cash provided by operating activities	137,618	79,636	134,899
Net cash acquired in business combinations	32,255us-gaap_CashAcquiredFromAcquisition	(154,170)us-gaap_CashAcquiredFromAcquisition	0us-gaap_CashAcquiredFromAcquisition
Investing Activities
Net cash provided by investing activities	(521,961)	(281,060)	8,403
Financing Activities
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	(96)	(32)	0
Cash dividends paid	(49,494)us-gaap_PaymentsOfDividendsCommonStock	(19,858)us-gaap_PaymentsOfDividendsCommonStock	(38,824)us-gaap_PaymentsOfDividendsCommonStock
Purchase and retirement of common stock	(622)	(429)	0
Proceeds from exercise of stock options	929	1,092	713
Excess tax benefit from stock-based compensation	205	1,203	0
Net cash provided by financing activities	392,952	(132,941)	76,335
Increase (decrease) in cash and cash equivalents	8,609	(334,365)	219,637
Cash and cash equivalents at beginning of period	179,561	513,926	294,289
Cash and cash equivalents at end of period	188,170	179,561	513,926
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Proceeds from Warrant Exercises	5,000	0	0
Operating Activities
Net Income (Loss)	81,574	60,016	46,143
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries	(66,681)	119,533	2,020
Stock-based compensation expense	2,859	2,844	1,622
Net changes in other assets and liabilities	(403)	6,830	(264)
Net cash provided by operating activities	17,349	189,223	49,521
Net cash acquired in business combinations	10,277	(53,159)	0
Investing Activities
Net cash provided by investing activities	10,277	(53,159)	0
Financing Activities
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	(96)	(32)	0
Cash dividends paid	(49,494)	(19,858)	(38,824)
Repayment of long-term subordinated debt	(14,636)	(51,000)	0
Purchase and retirement of common stock	(622)	(429)	0
Proceeds from exercise of stock options	929	1,092	713
Downstream stock offering proceeds to the Bank	0	(100,000)	0
Excess tax benefit from stock-based compensation	205	1,203	0
Net cash provided by financing activities	(58,714)	(169,024)	(38,111)
Increase (decrease) in cash and cash equivalents	(31,088)	(32,960)	11,410
Cash and cash equivalents at beginning of period	53,684	86,644	75,234
Cash and cash equivalents at end of period	$ 22,596	$ 53,684	$ 86,644

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Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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