CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating activities:
Net income	$ 20,241	$ 18,826
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	3,007	2,809
Amortization of intangible assets	1,179	1,086
Net accretion of premiums and discounts on securities, loans and borrowings	(1,477)	(998)
Stock-based compensation	1,220	1,223
Provision for loan losses	1,393	1,644
Amortization of mortgage servicing rights	142	188
Income from bank-owned life insurance policies	(283)	(271)
Gain on sales of investment securities	(47,791)	0
Loss on debt extinguishments	47,783	0
Net loss/(gain) from sale of loans and other assets	71	(171)
Net change in loans held for sale	2	562
Change in other assets and liabilities	(3,964)	3,997
Net cash provided by operating activities	21,523	28,895
Investing activities:
Proceeds from sales of available-for-sale investment securities	398,654	0
Proceeds from maturities of available-for-sale investment securities	52,802	36,742
Proceeds from maturities of held-to-maturity investment securities	8,315	4,555
Proceeds from sale of other investment securities	16,737	0
Purchases of available-for-sale investment securities	(121,665)	(549,254)
Purchases of held-to-maturity investment securities	(1,825)	(103,633)
Purchases of other securities	0	(8,190)
Net (increase) decrease in loans	2,607	8,238
Purchases of premises and equipment	(2,502)	(560)
Net cash provided by (used in) investing activities	353,123	(612,102)
Financing activities:
Net increase in deposits	146,785	156,762
Net change in borrowings, net of payments of $414,422 and $54	(414,422)	182,146
Issuance of common stock	4,912	60,425
Cash dividends paid	(10,699)	(9,609)
Tax benefits from share-based payment arrangements	518	660
Net cash (used in) provided by financing activities	(272,906)	390,384
Change in cash and cash equivalents	101,740	(192,823)
Cash and cash equivalents at beginning of period	228,558	324,878
Cash and cash equivalents at end of period	330,298	132,055
Supplemental disclosures of cash flow information:
Cash paid for interest	11,719	13,824
Cash paid for income taxes	4,168	3,091
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	10,735	10,216
Transfers from loans to other real estate	$ 2,396	$ 739