Subsequent Event (Details) - Apr. 30, 2021 - Subsequent Event $ in Millions	USD ($)	debtSeries	engine	airframe
Subsequent Event [Line Items]
Number of debt series issued | debtSeries		3
WEST VI
Subsequent Event [Line Items]
Number of assets used to secure debt			29	1
WEST VI | WEST VI Notes
Subsequent Event [Line Items]
Debt instrument, face amount	$ 336.7
WEST VI | WEST VI Series A Notes
Subsequent Event [Line Items]
Debt instrument, face amount	278.6
WEST VI | WEST VI Series B Notes
Subsequent Event [Line Items]
Debt instrument, face amount	38.7
WEST VI | WEST VI Series C Notes
Subsequent Event [Line Items]
Debt instrument, face amount	$ 19.4