Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Assets [Abstract]
Cash and due from banks	$ 154,652	$ 164,757
Interest-earning deposits in financial institutions	81,642	148,469
Total cash and cash equivalents	236,294	313,226
Securities available-for-sale, at fair value	1,809,364	1,567,177
Federal Home Loan Bank stock, at cost	17,250	40,609
Total investment securities	1,826,614	1,607,786
Gross loans and leases	12,493,397	11,904,684
Deferred fees and costs	(41,192)	(22,252)
Allowance for loan and lease losses	(103,271)	(84,455)
Total loans and leases, net	12,348,934	11,797,977
Equipment leased to others under operating leases	161,508	122,506
Premises and equipment, net	36,475	36,551
Foreclosed assets, net	33,216	43,721
Goodwill	1,728,380	1,720,479
Core deposit and customer relationship intangibles, net	12,704	17,204
Deferred tax asset, net	169,760	284,411
Other assets	260,220	290,744
Total assets	16,814,105	16,234,605
Liabilities and Equity [Abstract]
Noninterest-bearing deposits	3,508,682	2,931,352
Interest-bearing deposits	8,607,081	8,823,776
Total deposits	12,115,763	11,755,128
Borrowings	552,497	383,402
Subordinated debentures	435,417	433,583
Accrued interest payable and other liabilities	128,724	156,262
Total liabilities	13,232,401	12,728,375
Commitments and contingencies (Note 10)	0	0
Preferred stock ($0.01 par value; 5,000,000 shares authorized; none issued and outstanding)	0	0
Common stock ($0.01 par value, 200,000,000 shares authorized at September 30, 2015 and December 31, 2014; 104,431,508 and 104,219,197 shares issued, respectively, including 988,825 and 1,108,505 shares of unvested restricted stock, respectively)	1,044	1,042
Additional paid-in capital	3,665,173	3,807,167
Accumulated deficit	(57,934)	(285,712)
Treasury stock, at cost (1,377,814 and 1,197,180 shares at September 30, 2015 and December 31, 2014)	(51,038)	(42,647)
Accumulated other comprehensive income, net	24,459	26,380
Total stockholders' equity	3,581,704	3,506,230
Total liabilities and stockholders' equity	$ 16,814,105	$ 16,234,605