Notes Receivable - General Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2008	Dec. 31, 2020	Dec. 31, 2017	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Aggregate carrying values		$ 71,923,000			$ 110,135,000
Transition adjustment		(911,092,000)			(495,514,000)
Credit loss		32,784,000
Cumulative Effect, Period of Adoption, Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transition adjustment				$ (5,300,000)
Bonds A Series [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bond issued, face value		$ 95,000,000
Interest rates on bonds (as a percent)		8.00%
Maturity date of notes receivable		Jul. 01, 2034
Effective interest rates on bonds (as a percent)	8.04%
Present value of future debt service payments discounted	$ 93,800,000
Bonds B Series [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bond issued, face value		$ 50,000,000
Interest rates on bonds (as a percent)		10.00%
Maturity date of notes receivable		Sep. 01, 2037
Effective interest rates on bonds (as a percent)	11.42%
Present value of future debt service payments discounted	$ 38,300,000
Less portion recognized in other comprehensive income			$ 6,500,000
Bonds B Series [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transition adjustment				$ (5,200,000)
Bonds A and B Series [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Aggregate carrying values		$ 71,900,000			110,100,000
Credit loss reserve		38,000,000.0			$ 0
Credit loss		$ 38,000,000.0