Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Assets [Abstract]
Cash and due from banks	$ 226,471	$ 161,020
Interest-earning deposits in financial institutions	218,882	235,466
Total cash and cash equivalents	445,353	396,486
Securities available-for-sale, at fair value	3,347,546	3,559,437
Federal Home Loan Bank stock, at cost	24,214	19,710
Total investment securities	3,371,760	3,579,147
Gross loans and leases	14,703,326	14,528,165
Deferred fees, net	(61,866)	(49,911)
Allowance for loan and lease losses	143,289	115,111
Total loans and leases, net	14,498,171	14,363,143
Equipment leased to others under operating leases	204,062	197,452
Premises and equipment, net	38,718	39,197
Foreclosed assets, net	16,181	22,120
Goodwill	2,175,791	2,176,291
Core deposit and customer relationship intangibles, net	43,766	53,220
Deferred tax asset, net	24,413	126,389
Other assets	328,924	335,045
Total assets	21,147,139	21,288,490
Liabilities and Equity [Abstract]
Noninterest-bearing deposits	6,222,696	6,171,455
Interest-bearing deposits	8,925,313	9,494,727
Total deposits	15,148,009	15,666,182
Borrowings	918,208	621,914
Subordinated debentures	439,322	436,000
Accrued interest payable and other liabilities	128,296	166,703
Total liabilities	16,633,835	16,890,799
Commitments and contingencies (Note 8)
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 June 30, 2016 and December 31, 2015; 123,317,742 and 122,791,729 shares issued, respectively, including 1,407,486 and 1,211,951 shares of unvested restricted stock, respectively)	1,233	1,228
Additional paid-in capital	4,299,259	4,405,775
Retained earnings	186,531	13,907
Treasury stock, at cost (1,497,893 and 1,378,002 shares at June 30, 2016 and December 31, 2015)	(55,463)	(51,047)
Accumulated other comprehensive income, net	81,744	27,828
Total stockholders' equity	4,513,304	4,397,691
Total liabilities and stockholders' equity	$ 21,147,139	$ 21,288,490