Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 94,292	$ 88,575
Investing Activities
Proceeds from maturities, repayments, and calls of securities available-for-sale	216,900	125,244
Proceeds from sales of securities available-for-sale	57,255	24,947
Purchases of securities available-for-sale	(241,300)	(16,411)
Proceeds from maturities, repayments, and calls of securities held-to-maturity	4,016	3,814
Purchases of securities held-to-maturity	(1,184)	(1,998)
Net purchases of FHLB stock	(1,190)	(427)
Net increase in loans	(214,357)	(291,561)
Premiums paid for BOLI, net of claims	1,095	(73)
Proceeds from sales of OREO	13,820	14,293
Proceeds from sales of premises, furniture, and equipment	195	3,893
Purchases of premises, furniture, and equipment	(6,591)	(7,885)
Cash received from acquisitions, net of cash paid	0	139,486
Net cash used in investing activities	(171,341)	(6,678)
Financing Activities
Net increase in deposit accounts	408,692	119,440
Net increase in borrowed funds	31,949	23,085
Purchase of treasury stock	(120)	0
Payment for the termination of FHLB advances	0	(116,609)
Cash dividends paid	(20,132)	(16,556)
Restricted stock activity	(2,853)	(2,739)
Excess tax benefit related to share-based compensation	794	824
Net cash provided by financing activities	418,330	7,445
Net increase in cash and cash equivalents	341,281	89,342
Cash and cash equivalents at beginning of period	606,262	587,241
Cash and cash equivalents at end of period	947,543	676,583
Supplemental Disclosures of Cash Flow Information:
Income taxes paid	12,787	7,262
Interest paid to depositors and creditors	14,931	14,714
Dividends declared, but unpaid	7,137	6,028
Non-cash transfers of loans to OREO	11,956	13,277
Non-cash transfer of loans held-for-investment to loans held-for-sale	$ 15,068	$ 70,183