Operating Leases (Details) ft² in Millions	Dec. 31, 2019 USD ($) ft²	Dec. 31, 2018 USD ($)
gross leasable area percent leased	96.00%
office space leasable square feet | ft²	3.2
Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year	$ 157,940,000
Operating Leases, Future Minimum Payments Receivable, in Two Years	148,553,000	$ 113,653,000
Operating Leases, Future Minimum Payments Receivable, in Three Years	136,050,000	101,957,000
Operating Leases, Future Minimum Payments Receivable, in Four Years	125,103,000	93,326,000
Operating Leases, Future Minimum Payments Receivable, in Five Years	110,474,000	86,905,000
Operating Leases, Future Minimum Payments Receivable, Thereafter	441,586,000	378,216,000
Operating Leases, Future Minimum Payments Receivable	$ 1,119,706,000	888,764,000
Other Property [Member]
gross leasable area percent leased	43.40%
Office Building [Member]
Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year	$ 81,558,000
Operating Leases, Future Minimum Payments Receivable, in Two Years	80,263,000	61,704,000
Operating Leases, Future Minimum Payments Receivable, in Three Years	78,421,000	58,805,000
Operating Leases, Future Minimum Payments Receivable, in Four Years	76,897,000	58,108,000
Operating Leases, Future Minimum Payments Receivable, in Five Years	73,239,000	57,343,000
Operating Leases, Future Minimum Payments Receivable, Thereafter	336,842,000	298,469,000
Operating Leases, Future Minimum Payments Receivable	727,220,000	590,993,000
New Market Properties [Member]
Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year	76,382,000
Operating Leases, Future Minimum Payments Receivable, in Two Years	68,290,000	51,949,000
Operating Leases, Future Minimum Payments Receivable, in Three Years	57,629,000	43,152,000
Operating Leases, Future Minimum Payments Receivable, in Four Years	48,206,000	35,218,000
Operating Leases, Future Minimum Payments Receivable, in Five Years	37,235,000	29,562,000
Operating Leases, Future Minimum Payments Receivable, Thereafter	104,744,000	79,747,000
Operating Leases, Future Minimum Payments Receivable	$ 392,486,000	$ 297,771,000