Derivatives and Hedging Activities Narratives (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 28, 2019
Derivative [Line Items]
Reclassifications from accumulated other comprehensive loss into earnings as a result of the discontinuance of cash-flow hedges		$ 0	$ 0	$ 0
Maximum length of time which we are hedging our exposure to the variability in future cash flows for forecasted transactions		2 years
Deferred net losses on derivatives accumulated in other comprehensive loss related to cash flow hedges expected to be reclassified to earnings during the next 12 months		$ 7,000,000.0
Aggregate fair value of all uncleared derivatives in a net-liability position (before cash collateral and related accrued interest)		38,700,000
Post-haircut value of collateral already posted		38,600,000
Rating Downgrade from AAPlus to AA or AAMinus [Member]
Derivative [Line Items]
Incremental collateral	[1]	302,000
Rating Downgrade From AMinus to below AMinus [Member]
Derivative [Line Items]
Incremental collateral	[1]	5,801,000
Rating Downgrade From AAMinus to APlus, A or AMinus [Member]
Derivative [Line Items]
Incremental collateral	[1]	$ 0
Terminated Derivative [Member]
Derivative [Line Items]
Terminated derivatives notional amount					$ 611,900,000
Terminated derivatives settlement amount					(251,500,000)
Replacement Derivatives [Member]
Derivative [Line Items]
Replacement derivatives notional amount					611,900,000
Replacement derivatives settlement amount					$ 251,500,000

[1] Ratings are expressed in this table according to S&P's conventions but include the equivalent of such rating by Moody's. If there is a split rating, the lower rating is used.