Notes Receivable and Allowance for Credit Losses - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	$ 143,699	$ 133,014
Accounting standards update	us-gaap:AccountingStandardsUpdate201613Member
Loan reserves	$ 15,850	4,556	$ 4,685
Retained earnings	1,002,132	968,833
Loans and financing receivable	97,935	103,054
Mezzanine & Other Notes Receivable | Impaired Loans
Notes Receivable and Allowance for Losses [Line Items]
Average notes receivable, nonaccrual status	29,900	1,700
Variable Interest Entity, Not Primary Beneficiary | Mezzanine & Other Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Loans and financing receivable	125,800	126,500
Variable Interest Entity, Not Primary Beneficiary | Interest Rate Below Market Reduction | Mezzanine & Other Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Loans and financing receivable	14,200	16,300
Receivable with Imputed Interest, discount	$ 1,100	1,300
Cumulative Effect, Period of Adoption. Adjusted Balance | Accounting Standards Update 2016-13
Notes Receivable and Allowance for Losses [Line Items]
Loan reserves		12,900
Cumulative Effect, Period of Adoption, Adjustment
Notes Receivable and Allowance for Losses [Line Items]
Loan reserves		8,348
Retained earnings		$ 6,800