Financing Receivables (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019
Schedule of Financial Receivables [Line Items]
Lease investment with non-investment grade counterparties, gross	$ 295.0
Lease investment with non-investment grade counterparties, net of deferred taxes	7.0
Expected claim proceeds	31.5
REMA Funded credit support	$ 36.0
Powerton Station [Member]
Schedule of Financial Receivables [Line Items]
Counterparties’ S&P Credit Ratings	BB
Subsequent Event [Member]
Schedule of Financial Receivables [Line Items]
Expected tax payment for REMA restructuring		$ 120.0