Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	$ 20,973	$ 19,802
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangibles	3,323	3,333
Provision for loan losses	1,500	600
Deferred tax expense	456	1,748
Increase in cash surrender value of Bank-owned life insurance	(1,332)	(1,348)
Net amortization of premiums and discounts on securities	2,401	2,655
Accretion of net deferred loan fees	(687)	(946)
Amortization of premiums on purchased loans, net	198	292
Net increase in loans originated for sale	(2,598)	(3,869)
Proceeds from sales of loans originated for sale	2,921	4,056
Proceeds from sales of foreclosed assets	1,063	288
ESOP expense	746	687
Allocation of stock award shares	723	852
Allocation of stock options	46	72
Net gain on sale of loans	(323)	(187)
Net gain on securities transactions	(96)	(2)
Net gain on sale of premises and equipment	(4)	(5)
Net (gain) loss on sale of foreclosed assets	(26)	32
Decrease in accrued interest receivable	367	686
Increase in other assets	(2,659)	(4,621)
Increase (decrease) in other liabilities	785	(2,897)
Net cash provided by operating activities	27,777	21,228
Cash flows from investing activities:
Proceeds from maturities, calls and paydowns of investment securities held to maturity	11,805	5,343
Purchases of investment securities held to maturity	(11,259)	(10,220)
Proceeds from sales of securities	2,106	0
Proceeds from maturities, calls and paydowns of securities available for sale	40,818	45,848
Purchases of securities available for sale	(52,513)	(14,769)
Net decrease in Federal Home Loan Bank stock	6,046	2,334
Purchases of loans	(28,590)	(23,692)
Net increase in loans	(72,894)	(15,994)
Proceeds from sales of premises and equipment	4	5
Purchases of premises and equipment	(1,758)	(2,148)
Net cash used in investing activities	(106,235)	(13,293)
Cash flows from financing activities:
Net increase in deposits	230,875	30,528
Increase in mortgage escrow deposits	2,291	2,004
Purchases of treasury stock	(2,697)	(1,882)
Cash dividends paid to stockholders	(11,321)	(10,798)
Shares issued through the dividend reinvestment plan	365	377
Stock options exercised	2,321	395
Proceeds from long-term borrowings	167,858	82,917
Payments on long-term borrowings	(206,068)	(87,000)
Net decrease in short-term borrowings	(99,281)	(37,364)
Net cash provided by (used in) financing activities	84,343	(20,823)
Net increase (decrease) in cash and cash equivalents	5,885	(12,888)
Cash and cash equivalents at beginning of period	102,226	103,762
Cash and cash equivalents at end of period	108,111	90,874
Cash paid during the period for:
Interest on deposits and borrowings	10,856	9,804
Income taxes	3,125	8,057
Non-cash investing activities:
Transfer of loans receivable to foreclosed assets	$ 1,520	$ 1,146