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Debt Obligations - Narrative (Details)		1 Months Ended	3 Months Ended
	Mar. 03, 2020	Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 03, 2020	Mar. 03, 2020 engine	Mar. 03, 2020 USD ($)	Mar. 03, 2020 airframe
Long Term Debt
Loss on debt extinguishment			$ 4,688,000	$ 0
WEST V Series A Notes
Long Term Debt
Fixed rate (as a percent)		3.23%	3.23%
WEST V Series B Notes
Long Term Debt
Fixed rate (as a percent)		4.21%	4.21%
WEST V Series C Notes
Long Term Debt
Fixed rate (as a percent)		6.66%	6.66%
WEST II Series A Notes
Long Term Debt
Fixed rate (as a percent)		5.50%	5.50%
Loss on debt extinguishment		$ 4,700,000
WEST V
Long Term Debt
Number of assets used to secure debt						54		3
WEST V | WEST V Notes
Long Term Debt
Debt instrument, face amount							$ 366,200,000
WEST V | WEST V Series A Notes
Long Term Debt
Debt instrument, face amount							303,000,000.0
Fixed rate (as a percent)					3.228%
Debt instrument, term	8 years
Notes issue price, percentage of par	99.99859%
WEST V | WEST V Series B Notes
Long Term Debt
Debt instrument, face amount							42,100,000
Fixed rate (as a percent)					4.212%
Debt instrument, term	8 years
Notes issue price, percentage of par	99.99493%
WEST V | WEST V Series C Notes
Long Term Debt
Debt instrument, face amount							$ 21,100,000
Fixed rate (as a percent)					6.657%
Debt instrument, term	8 years
Notes issue price, percentage of par	99.99918%
Assets Under Purchase Agreement With WEST V | WEST V
Long Term Debt
Number of assets used to secure debt						25		3

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