Derivative and Hedging Activities Cumulative Basis Adjustment for Fair Value Hedges (Details) - Designated as hedging instruments $ in Thousands	Dec. 31, 2019 USD ($)
Balance Sheet Recording of Fair Value Hedge [Line Items]
Deferred (Gain) Loss on Discontinuation of Fair Value Hedge	$ 5,000
Underlying Hedged Asset, Amortized Cost Basis	893,000
Derivative Liability Notional Amount, Terminated	500,000
Carrying Amount of the Hedged Assets/(Liabilities)
Balance Sheet Recording of Fair Value Hedge [Line Items]
Net Amounts Presented on the Consolidated Balance Sheets	505,371
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)(b)
Balance Sheet Recording of Fair Value Hedge [Line Items]
Deferred (Gain) Loss on Discontinuation of Fair Value Hedge	$ 5,371