Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 43,202	$ 42,470
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,435	(7,001)
Net (gain) loss on disposal of property and equipment	(856)	(79)
Depreciation and amortization	9,090	7,786
Net premium amortization on investment securities	7,021	7,088
Net gains on investment securities transactions	(52)	(88)
Net gains on sales of mortgage loans held for sale	(10,759)	(7,601)
Net gain on sale of OREO	(1,736)	(766)
Write-downs of OREO and other assets pending disposal	106	10
Net reversal of impairment of mortgage servicing rights	(71)	(56)
Deferred income tax expense	9,108	3,760
Net increase in cash surrender value of company-owned life insurance policies	(1,304)	(1,724)
Stock-based compensation expense	2,319	2,154
Tax benefits from stock-based compensation expense	804	1,225
Excess tax benefits from stock-based compensation	(530)	(1,211)
Originations of loans held for sale	(561,779)	(412,050)
Proceeds from sales of loans held for sale	546,871	402,825
Changes in operating assets and liabilities:
Increase in interest receivable	(1,945)	(47)
Increase in other assets	(1,034)	(1,929)
Decrease in accrued interest payable	(467)	353
Decrease in accounts payable and accrued expenses	(12,268)	(4,788)
Net cash provided by operating activities	28,155	30,331
Cash flows from investing activities:
Purchases of held-to-maturity investment securities	(27,640)	(4,141)
Purchases of available-for-sale investment securities	(223,483)	(175,823)
Proceeds from maturities and paydowns of held-to-maturity investment securities	55,654	9,347
Proceeds from maturities and paydowns of available-for-sale investment securities	337,538	243,355
Purchases of company-owned life insurance	(22,500)	(15,000)
Proceeds from sales of mortgage servicing rights	0	266
Extensions of credit to customers, net of repayments	(190,392)	(155,523)
Recoveries of loans charged-off	3,285	5,345
Proceeds from sales of OREO	7,807	4,234
Capital expenditures, net of sales	514	(6,309)
Net cash used in investing activities	(59,217)	(94,249)
Cash flows from financing activities:
Net increase (decrease) in deposits	(201,811)	45,292
Net increase (decrease) in repurchase agreements	(33,105)	5,548
Net increase (decrease) in other borrowed funds	(6)	17
Repayments of long-term debt	(30)	(24)
Advances on long-term debt	5,031	0
Proceeds from issuance of common stock	1,670	3,547
Excess tax benefits from stock-based compensation	530	1,211
Purchase and retirement of common stock	(15,264)	(8,764)
Dividends paid to common stockholders	(18,189)	(14,088)
Net cash provided by (used in) financing activities	(261,174)	32,739
Net increase (decrease) in cash and cash equivalents	(292,236)	(31,179)
Cash and cash equivalents at beginning of period	798,670	534,827
Cash and cash equivalents at end of period	506,434	503,648
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	18,450	16,190
Cash paid during the period for interest expense	$ 9,364	$ 8,656