Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 30, 2014
Operating activities:
Net income	$ 9,284		$ 9,889	$ 27,541	$ 26,100
Adjustments to reconcile net income to net cash provided by operating activities:
Provision (credit) for loan losses			(2,100)	0	(400)	$ (400)
Depreciation, amortization and accretion, net				5,088	3,226
Deferred income tax expense (benefit)				1,326	(252)
Loss on sale of securities available for sale					9
Gain on sales of mortgage loans held for sale				(1,611)	(769)
Origination of mortgage loans held for sale				(90,997)	(64,332)
Proceeds from sale of mortgage loans held for sale				90,816	63,159
Bank owned life insurance income	(222)		(229)	(670)	(699)
Loss (gain) on the disposal of premises and equipment				3	(30)
Loss (gain) on the sale of other real estate	(12)		7	153	(342)
Stock compensation expense				1,561	1,459
Excess tax benefits from share-based compensation arrangements				(366)	(257)
(Increase) decrease in accrued interest receivable and other assets				(1,049)	1,107
Increase in accrued interest payable and other liabilities				2,509	2,049
Net cash provided by operating activities				34,304	30,028
Investing activities:
Purchases of securities available for sale				(203,465)	(220,296)
Proceeds from sale of securities available for sale		$ 5,900		5,934	7,732		$ 7,700
Proceeds from maturities of securities available for sale				206,734	256,948
Net increase in loans				(90,224)	(66,748)
Purchases of premises and equipment				(3,136)	(1,517)
Proceeds from disposal of premises and equipment					344
Proceeds from sale of foreclosed assets				2,332	4,768
Net cash used in investing activities				(81,825)	(18,769)
Financing activities:
Net increase in deposits				17,951	26,884
Net increase (decrease) in securities sold under agreements to repurchase and federal funds purchased				12,709	(34,659)
Proceeds from Federal Home Loan Bank advances				78,200	32,740
Repayments of Federal Home Loan Bank advances				(71,333)	(30,150)
Issuance of common stock for options and performance stock units				1,994	1,445
Excess tax benefits from share-based compensation arrangements				366	257
Common stock repurchases				(910)	(564)
Cash dividends paid				(10,503)	(9,534)
Net cash provided by (used in) financing activities				28,474	(13,581)
Net decrease in cash and cash equivalents				(19,047)	(2,322)
Cash and cash equivalents at beginning of period		$ 74,241		74,241	70,770	70,770	$ 70,770
Cash and cash equivalents at end of period	$ 55,194		$ 68,448	55,194	68,448	$ 74,241
Supplemental cash flow information:
Income tax payments				10,177	8,764
Cash paid for interest				3,640	4,063
Supplemental non-cash activity:
Transfers from loans to other real estate owned				$ 1,043	$ 1,780