Short-term Borrowings and Other Debt Obligations LC Credit Agreement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 12, 2019
LC Credit Agreement [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 195.0
Letter Of Credit Fee Percentage	0.125%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.50%
Letters of Credit Outstanding, Amount		$ 65.8
Minimum liquidity amount	$ 200.0
LIBOR | LC Credit Agreement [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.50%
Committed Letters of Credit [Member]
Short-term Debt [Line Items]
Letters of Credit Outstanding, Amount	$ 399.0
Letters of Credit Outstanding, Cash Collateral	$ 152.0