Summary of Significant Accounting Policies (Accounts Receivable, Net) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 81,935	$ 66,726
Reserve for uncollectible amounts	29,900	33,000
Reserve for uncollectible amounts under ASC 842	26,400	27,300
Reserve for uncollectible amounts under ASC 450		5,700
Collectibility of receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserve for uncollectible amounts under ASC 450	3,600
Tenant receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	9,150	4,339
Straight-line rent receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	68,709	59,288
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 4,076	$ 3,099