Offsetting Assets and Liabilities Cash and Money Market Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets [Member] | Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	$ 568,334	$ 619,758
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	568,334	619,758
Gross amounts not offset in the balance sheet	0	0
Cash Collateral Received/Pledged	0	0
Net amount	568,334	619,758
Assets [Member] | Derivative Financial Instruments, Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	64,195	77,638
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	64,195	77,638
Gross amounts not offset in the balance sheet	(17,118)	(6,990)
Cash Collateral Received/Pledged	(162)
Net amount	46,915	70,648
Assets [Member] | Assets, Total [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	632,529	697,396
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	632,529	697,396
Gross amounts not offset in the balance sheet	(17,118)	(6,990)
Cash Collateral Received/Pledged	(162)	0
Net amount	615,249	690,406
Other Liabilities [Member] | Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	827,269	346,987
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	827,269	346,987
Gross amounts not offset in the balance sheet	0	0
Cash Collateral Received/Pledged	0	0
Net amount	827,269	346,987
Other Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	59,221	72,568
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	59,221	72,568
Gross amounts not offset in the balance sheet	(17,118)	(6,990)
Cash Collateral Received/Pledged	(16,570)	(60,923)
Net amount	25,533	4,655
Other Liabilities [Member] | Liabilities, Total [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	886,490	419,555
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	886,490	419,555
Gross amounts not offset in the balance sheet	(17,118)	(6,990)
Cash Collateral Received/Pledged	(16,570)	(60,923)
Net amount	$ 852,802	$ 351,642