CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities:
Net income	$ 40,106	$ 26,257
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	4,001	3,669
Amortization of intangible assets	4,798	2,768
Net accretion on securities, loans and borrowings	(2,214)	(406)
Stock-based compensation	1,715	1,410
Provision for loan losses	3,679	1,828
Amortization of mortgage servicing rights	117	126
Income from bank-owned life insurance policies	(388)	(368)
Net gain on sale of loans and other assets	(80)	(53)
Change in other assets and other liabilities	9,174	7,430
Net cash provided by operating activities	60,908	42,661
Investing activities:
Proceeds from maturities of available-for-sale investment securities	27,363	33,479
Proceeds from maturities of other investment securities	4,960	8,709
Purchases of available-for-sale investment securities	(23,434)	(16,784)
Purchases of other securities	(21)	(505)
Net change in loans	25,900	12,197
Cash paid for acquisitions, net of cash acquired of $16 and $11,063, respectively	(1,464)	(63,517)
Purchases of premises and equipment, net	(1,556)	(2,088)
Net cash provided by/(used in) investing activities	31,748	(28,509)
Financing activities:
Net increase in deposits	326,672	260,923
Net change in borrowings	(81,338)	(146,200)
Issuance of common stock	570	1,809
Purchases of treasury stock	(81)	0
Sales of treasury stock	2,546	2,151
Increase in deferred compensation arrangements	81	0
Cash dividends paid	(17,281)	(14,186)
Withholding taxes paid on share-based compensation	(964)	(1,320)
Net cash provided by financing activities	230,205	103,177
Change in cash and cash equivalents	322,861	117,329
Cash and cash equivalents at beginning of period	221,038	173,857
Cash and cash equivalents at end of period	543,899	291,186
Supplemental disclosures of cash flow information:
Cash paid for interest	3,757	2,707
Cash paid for income taxes	564	9,044
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	17,438	14,773
Transfers from loans to other real estate	942	920
Acquisitions:
Common stock issued	0	78,483
Fair value of assets acquired, excluding acquired cash and intangibles	27	31,599
Fair value of liabilities assumed	$ 31	$ 30,500