Consolidated Statements Of Cash Flows (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Operating Activities:
Net income	$ 23,210,000	$ 16,402,000
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	17,400,000	25,344,000
Depreciation and amortization	5,627,000	5,551,000
Stock-based compensation expense	2,289,000	1,094,000
Tax benefit from stock-based compensation arrangements	12,000	235,000
Excess tax benefits from stock-based compensation arrangements	(643,000)	(194,000)
Net (accretion) amortization of (discount) premium on securities	(2,092,000)	4,176,000
Mortgage servicing rights fair value change and amortization, net	(514,000)	(140,000)
Originations and purchases of mortgage loans held-for-sale	(714,655,000)	(562,088,000)
Proceeds from sales of mortgage loans held-for-sale	699,315,000	843,209,000
Bank owned life insurance income, net of claims	(919,000)	(876,000)
Decrease in trading securities, net	1,350,000	2,650,000
Net increase in brokerage customer receivables	(3,160,000)	(812,000)
Gain on mortgage loans sold	(14,464,000)	(4,160,000)
Gain on available-for-sale securities, net	(816,000)	(106,000)
Gain on bargain purchases	(840,000)	(9,838,000)	(38,000,000)
Debt defeasance costs	848,000
Loss on sales of premises and equipment, net	12,000
Decrease in accrued interest receivable and other assets, net	107,929,000	47,043,000
Decrease in accrued interest payable and other liabilities, net	(11,689,000)	(16,406,000)
Net Cash Provided by Operating Activities	108,200,000	351,084,000
Investing Activities:
Proceeds from maturities of available-for-sale securities	280,110,000	284,469,000
Proceeds from sales of available-for-sale securities	737,369,000	50,142,000
Purchases of available-for-sale securities	(952,853,000)	(541,199,000)
Net cash received for acquisitions	8,191,000	21,371,000
Net increase in interest-bearing deposits with banks	(151,033,000)	(56,222,000)
Net (increase) decrease in loans	(206,246,000)	17,691,000
Purchases of premises and equipment, net	(8,501,000)	(10,557,000)
Net Cash Used for Investing Activities	(292,963,000)	(234,305,000)
Financing Activities:
Increase (decrease) in deposit accounts	269,326,000	(100,938,000)
Decrease in other borrowings, net	(34,141,000)	(10,808,000)
Decrease in Federal Home Loan Bank advances, net	(8,000,000)
Excess tax benefits from stock-based compensation arrangements	643,000	194,000
Net proceeds from issuance of preferred stock	122,690,000
Debt defeasance	(172,848,000)
Issuance of common shares resulting from exercise of stock options, employee stock purchase plan and conversion of common stock warrants	8,699,000	905,000
Common stock repurchases	(6,447,000)	(74,000)
Dividends paid	(4,261,000)	(4,144,000)
Net Cash Provided by (Used for) Financing Activities	175,661,000	(114,865,000)
Net (Decrease) Increase in Cash and Cash Equivalents	(9,102,000)	1,914,000
Cash and Cash Equivalents at Beginning of Period	169,704,000	172,580,000	172,580,000
Cash and Cash Equivalents at End of Period	$ 160,602,000	$ 174,494,000	$ 169,704,000