Related Party Transactions (Narrative) (Details) - USD ($)		3 Months Ended						6 Months Ended		20 Months Ended
	Oct. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Mar. 17, 2020
Related Party Transaction [Line Items]
Percentage of shares held by manager related party		15.64%						15.64%		15.64%
Base management fees to be settled		$ 4,000,000	$ 7,000,000	$ 9,000,000	$ 8,000,000	$ 7,000,000	$ 8,000,000
Percentage of cap on base management fee										1.00%
Disposition agreement, qualifying termination event, minimum due upon sale or sales of businesses	$ 50,000,000
Disposition agreement, qualifying termination event, perccentage applied above threshold	1.50%
Disposition agreement, qualifying termination event, threshold, net proceeds	$ 500,000,000
Disposition agreement, potential extension period for additional payment subject to qualifying termination event occurring on or prior to January 1, 2022	6 months
Disposition agreement, qualifying termination event, additional payment	$ 25,000,000
Disposition agreement, minimum management fee for years one and two	$ 20,000,000
Disposition agreement, minimum management fee for years one and two	2 years
Disposition agreement, minimum management fee for years three through six	$ 10,000,000
Recapture amount of previously waived management fees	$ 8,500,000
Disposition agreement, maximum period without qualifying termination event	sixth anniversary
MIC Corporate | Revolving Credit Facility
Related Party Transaction [Line Items]
Borrowing capacity		$ 600,000,000						$ 600,000,000		$ 600,000,000	$ 600,000,000
Management
Related Party Transaction [Line Items]
Shares of the Company held by Manager, a related party (in shares)		13,600,444		13,253,791				13,600,444		13,600,444
Base management fees to be settled		$ 4,000,000				7,000,000		$ 11,000,000	$ 15,000,000
Reimbursement of out-of-pocket expenses		16,000				331,000		304,000	577,000
Legal fees		60,000
Macquarie Capital Funding LLC | Revolving Credit Facility
Related Party Transaction [Line Items]
Borrowing capacity		40,000,000						40,000,000		$ 40,000,000
Macquarie Capital Funding LLC | MIC Corporate | Revolving Credit Facility
Related Party Transaction [Line Items]
Interest costs incurred		274,000				$ 41,000		361,000	$ 75,000
Indirect Subsidiaries Within Macquarie Group | IMTT
Related Party Transaction [Line Items]
Revenues		$ 1,000,000						2,000,000
Advisory Services | Former Board of Director
Related Party Transaction [Line Items]
Reimbursement of out-of-pocket expenses								$ 25,000
Minimum
Related Party Transaction [Line Items]
Disposition agreement, percentage of net proceeds due upon sale or sales of businesses	2.90%
Maximum
Related Party Transaction [Line Items]
Disposition agreement, percentage of net proceeds due upon sale or sales of businesses	6.10%