Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 83,722	$ 73,631	$ 70,534
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangibles	13,714	11,133	8,776
Provision for loan losses	4,350	4,650	5,500
Deferred tax expense	326	3,666	5,531
Increase in cash surrender value of Bank-owned Life Insurance	(5,345)	(5,633)	(6,596)
Net amortization of premiums and discounts on securities	10,613	10,461	12,942
Accretion of net deferred loan fees	(4,624)	(3,364)	(3,877)
Amortization of premiums on purchased loans, net	1,100	694	1,286
Net increase in loans originated for sale	(11,918)	(12,609)	(30,977)
Proceeds from sales of loans originated for sale	12,799	14,018	32,447
Proceeds from sales of foreclosed assets	4,443	6,494	13,686
ESOP expense	2,997	2,654	2,559
Allocation of stock award shares	4,625	6,359	4,869
Allocation of stock options	272	298	297
Net gain on sale of loans	(881)	(1,409)	(1,470)
Net gain on securities transactions	(654)	(251)	(996)
Impairment charge on securities	0	0	434
Net gain on sale of premises and equipment	(4)	(5)	(42)
Net gain on sale of foreclosed assets	(592)	(516)	(403)
(Increase) decrease in accrued interest receivable	(538)	787	1,046
(Increase) decrease in other assets	(4,912)	(10,660)	4,202
Increase in other liabilities	5,373	7,721	173
Net cash provided by operating activities	114,866	108,119	119,921
Cash flows from investing activities:
Proceeds from maturities, calls and paydowns of investment securities held to maturity	37,271	41,057	97,974
Purchases of investment securities held to maturity	(44,254)	(73,397)	(97,964)
Proceeds from sales of securities available for sale	14,005	25,033	14,834
Proceeds from maturities calls and paydowns of securities available for sale	212,095	207,531	351,472
Purchases of securities available for sale	(129,720)	(63,835)	(303,334)
Net increase in Federal Home Loan Bank stock	(8,392)	(11,719)	(20,527)
Net cash and cash equivalents (paid) received in acquisition	(25,855)	68,650	0
BOLI benefits paid	776	0	0
Purchases of loans	(95,283)	(130,540)	(34,766)
Net increase in loans	(363,436)	(129,240)	(259,359)
Proceeds from sales of premises and equipment	19	1,903	35
Purchases of premises and equipment	(5,909)	(16,441)	(7,709)
Net cash used in investing activities	(408,683)	(80,998)	(259,344)
Cash flows from financing activities:
Net increase (decrease) in deposits	131,464	(179,886)	(226,504)
Increase (decrease) in mortgage escrow deposits	1,696	1,250	(666)
Purchase of treasury stock	(1,988)	(4,420)	(5,899)
Cash dividends paid to stockholders	(41,285)	(36,118)	(32,320)
Shares issued to dividend reinvestment plan	1,447	1,336	1,244
Stock options exercised	3,166	117	354
Proceeds from long-term borrowings	694,937	595,063	301,000
Payments on long-term borrowings	(549,935)	(289,757)	(79,090)
Net increase (decrease) in short-term borrowings	52,779	(112,168)	178,705
Net cash provided by (used in) financing activities	292,281	(24,583)	136,824
Net (decrease) increase in cash and cash equivalents	(1,536)	2,538	(2,599)
Cash and cash equivalents at beginning of period	103,762	101,224	103,823
Cash and cash equivalents at end of period	102,226	103,762	101,224
Cash paid during the period for:
Interest on deposits and borrowings	41,663	39,952	36,727
Income taxes	40,620	25,776	29,119
Non cash investing activities:
Transfer of loans receivable to foreclosed assets	10,074	5,382	6,602
Non-cash assets acquired:
Investment securities available for sale	0	157,635	0
Loans	0	631,209	0
Bank-owned life insurance	0	22,319	0
Goodwill and other intangible assets, net	25,323	50,222	0
Other assets	1,270	33,939	0
Total non-cash assets acquired	26,593	895,324	0
Liabilities assumed:
Deposits	0	769,936	0
Borrowings	0	112,835	0
Other Liabilities	400	(2,314)	0
Total liabilities assumed	400	880,457	0
Common stock issued for acquisitions	$ 0	$ 83,517	$ 0