Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating Activities
Net income	$ 29,003	$ 24,866
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses, net	(742)	(2,838)
Depreciation and amortization	8,756	8,380
Net amortization of securities	1,958	1,868
Securities gains, net	(389)	(204)
Gains on sales of loans, net	(1,839)	(10,165)
Deferred income tax provision	2,400	2,157
Proceeds from sales of loans held for sale	186,788	402,159
Purchases and originations of loans held for sale	(162,937)	(382,425)
Originations and sales of mortgage servicing rights, net	(2,315)	(5,521)
Increase in bank-owned life insurance	(1,166)	(158)
Net decrease (increase) in other assets	7,891	(44,916)
Net decrease in other liabilities	(14,172)	(5,740)
Other operating activities, net	4,159	1,903
Net cash provided by (used in) operating activities	57,395	(10,634)
Investing Activities
Proceeds from calls and maturities of securities held to maturity	17,411	3,580
Proceeds from calls and maturities of securities available for sale	80,309	272,858
Proceeds from sales of securities available for sale	26,274	38,742
Purchases of securities held to maturity	(2,968)	(35,045)
Purchases of securities available for sale	(289,931)	(667,299)
Net decrease in federal funds sold and securities purchased under reverse repurchase agreements	7,253	1,120
Net (increase) decrease in loans	(78,370)	145,517
Purchases of premises and equipment	(2,337)	(2,228)
Proceeds from sales of premises and equipment	2,251	0
Proceeds from sales of other real estate	7,330	8,297
Net cash received in business combinations	0	89,037
Net cash used in investing activities	(232,778)	(145,421)
Financing Activities
Net increase in deposits	262,217	272,660
Net increase (decrease) in federal funds purchased and securities sold under repurchase agreements	7,754	(69,060)
Net increase (decrease) in short-term borrowings	16	(19,936)
Payments on long-term FHLB advances	(60)	(82)
Common stock dividends	(15,597)	(15,560)
Common stock issued-net, long-term incentive plans	(792)	(829)
Excess tax (expense) benefit from stock-based compensation arrangements	(97)	269
Net cash provided by financing activities	253,441	167,462
Increase in cash and cash equivalents	78,058	11,407
Cash and cash equivalents at beginning of period	345,761	231,489
Cash and cash equivalents at end of period	$ 423,819	$ 242,896