Short-Term Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Short-term borrowings	$ 594,733	$ 987,184
Master Notes [Member]
Short-term Debt [Line Items]
Short-term borrowings	0	410,258
Repurchase Agreements [Member]
Short-term Debt [Line Items]
Short-term borrowings	592,182	294,426
Federal Home Loan Bank Advances [Member]
Short-term Debt [Line Items]
Short-term borrowings	0	80,000
Maturities Of Debt	80,000
Federal Funds Purchased [Member]
Short-term Debt [Line Items]
Short-term borrowings	2,551	2,551
Unsecured Debt [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	740,000
Secured Debt [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	5,570,000
Subordinated Debt Obligations [Member]
Short-term Debt [Line Items]
Short-term borrowings	0	$ 199,949
Maturities Of Debt	$ 199,900