Short-term Funding Short-term Funding, Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 383,568
Gross amounts of recognized liabilities for repurchase agreements	383,568	$ 384,221
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	383,568
Maturity Overnight and on Demand [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	383,568
Maturity Overnight and on Demand [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	383,568
Maturity Less than 30 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0
Maturity Less than 30 Days [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0
Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0
Maturity 30 to 90 Days [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0
Maturity Greater than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0
Maturity Greater than 90 Days [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 0