Parent Company Only Financials (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ASSETS
Cash and due from banks	$ 563,304	$ 454,958
Investment securities available for sale, at fair value	4,926,758	4,937,483
Other assets	926,417	983,105
Total assets	23,487,735	21,924,217
LIABILITIES AND STOCKHOLDERS' EQUITY
Commercial paper	51,484	0
Senior notes, at par	585,000	430,000
Junior subordinated debentures, at par	0	211,340
Subordinated debt, at par	25,821	25,821
Long-term funding	1,015,346	1,177,071
Accrued expenses and other liabilities	192,843	196,166
Total liabilities	20,551,336	19,058,423
Preferred equity	63,272	63,272
Total stockholders' equity	2,936,399	2,865,794	3,158,791	2,738,608
Total liabilities and stockholders' equity	23,487,735	21,924,217
Parent Company [Member]
ASSETS
Cash and due from banks	159,725	126,835
Investment securities available for sale, at fair value	200,800	66,769
Due from Affiliates	47,455	47,230
Investment in subsidiaries	3,250,667	3,277,693
Other assets	74,507	76,037
Total assets	3,733,154	3,594,564
LIABILITIES AND STOCKHOLDERS' EQUITY
Commercial paper	51,245	0
Senior notes, at par	585,000	430,000
Junior subordinated debentures, at par	0	211,340
Subordinated debt, at par	25,821	25,821
Long-term funding capitalized costs	2,590	7,750
Long-term funding	613,411	674,911
Accrued expenses and other liabilities	132,099	53,859
Total liabilities	796,755	728,770
Preferred equity	63,272	63,272
Common equity	2,873,127	2,802,522
Total stockholders' equity	2,936,399	2,865,794
Total liabilities and stockholders' equity	$ 3,733,154	$ 3,594,564