Cash and Money Market Investments Cash and Money Market Investments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 62,589	$ 68,397
Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	379,947	282,248
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	379,947	282,248
Net amount	379,947	282,248
Assets, Total [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	437,630	347,931
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	437,630	347,931
Net amount	429,744	338,491
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	279,837	340,348
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	279,837	340,348
Net amount	279,837	340,348
Liabilities, Total [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	342,426	408,745
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	342,426	408,745
Net amount	304,520	370,098
Derivative Assets Included In Other Assets [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts recognized	57,683	65,683
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	57,683	65,683
Net amount	49,797	56,243
Derivative Liabilities Offsets In Other Assets-Offset [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	62,589	68,397
Net amount	24,683	29,750
Derivative Liability, Fair Value, Gross Liability	62,589	68,397
Cash collateral received/pledged [Domain] | Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	0	0
Cash collateral received/pledged [Domain] | Assets, Total [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	760	2,210
Cash collateral received/pledged [Domain] | Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	0	0
Cash collateral received/pledged [Domain] | Liabilities, Total [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	(29,260)	(26,997)
Cash collateral received/pledged [Domain] | Derivative Assets Included In Other Assets [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	760	2,210
Cash collateral received/pledged [Domain] | Derivative Liabilities Offsets In Other Assets-Offset [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	(29,260)	(26,997)
Types of Financial Instruments [Domain] | Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	0	0
Types of Financial Instruments [Domain] | Assets, Total [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	(8,646)	(11,650)
Types of Financial Instruments [Domain] | Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	0	0
Types of Financial Instruments [Domain] | Liabilities, Total [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	(8,646)	(11,650)
Types of Financial Instruments [Domain] | Derivative Assets Included In Other Assets [Member] | Assets [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	(8,646)	(11,650)
Types of Financial Instruments [Domain] | Derivative Liabilities Offsets In Other Assets-Offset [Member] | Other Liabilities [Member]
Gain (Loss) on Investments [Line Items]
Gross amounts not offset in the balance sheet	$ (8,646)	$ (11,650)