Operating Leases (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2019 USD ($)		Dec. 31, 2018 USD ($)		Dec. 31, 2017 USD ($)
Property Subject to or Available for Operating Lease [Line Items]
Property operating expense		$ 60,739		$ 29,654		$ 31,327
Operating Lease, Right-of-Use Asset		$ 211,187		$ 0
Number of Properties Subject to Ground Leases		58		57
Operating Leases, Future Minimum Payments Receivable [Abstract]
2020		$ 549,277
2021		542,453
2022		527,410
2023		497,498
2024		475,239
Thereafter		3,933,476
Total		6,525,353
Operating Lease, Liability		235,650		$ 0
Straight-Line Rent Receivable		73,382	[1]	73,332
Total Operating Leased Assets		235,756
General and Administrative Expense		46,371		48,889		43,383
Operating Leases, Income Statement, Lease Revenue		(593,022)		(509,086)		(441,187)
Lease, Cost		2,073
operating leases [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
2020	[2]	525,809		520,139	[3]
2021	[2]	518,590		503,344	[3]
2022	[2]	504,119		492,165	[3]
2023	[2]	474,889		477,671	[3]
2024	[2]	453,043		449,686	[3]
Thereafter	[2]	3,707,326		3,953,717	[3]
Total	[2]	$ 6,183,776		6,396,722	[3]
Ground Lease Arrangement [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating Lease, Weighted Average Remaining Lease Term		16 years
Property operating expense		$ 24,656
Operating Lease, Right-of-Use Asset		205,997
Operating Leases, Future Minimum Payments Due, Next Twelve Months		24,085	[4]	22,867	[5]
Operating Leases, Future Minimum Payments, Due in Two Years		24,529	[4]	23,236	[5]
Operating Leases, Future Minimum Payments, Due in Three Years		23,961	[4]	23,600	[5]
Operating Leases, Future Minimum Payments, Due in Four Years		23,283	[4]	22,996	[5]
Operating Leases, Future Minimum Payments, Due in Five Years		22,871	[4]	22,303	[5]
Operating Leases, Future Minimum Payments, Due Thereafter		243,411	[4]	257,446	[5]
Operating Leases, Future Minimum Payments Due		362,140	[4]	372,448	[5]
Operating Leases, Future Minimum Payments Receivable [Abstract]
2020	[2]	23,468
2021	[2]	23,863
2022	[2]	23,291
2023	[2]	22,609
2024	[2]	22,196
Thereafter	[2]	226,150
Total	[2]	341,577
Receivable with Imputed Interest, Discount	[4]	131,901
Operating Lease, Liability	[4]	$ 230,239
Operating Lease, Weighted Average Discount Rate, Percent		4.96%
Office Lease [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating Lease, Weighted Average Remaining Lease Term		6 years 9 months 18 days
Operating Lease, Right-of-Use Asset		$ 5,190
Operating Leases, Future Minimum Payments Due, Next Twelve Months	[6]	856		856	[5]
Operating Leases, Future Minimum Payments, Due in Two Years	[6]	884		856	[5]
Operating Leases, Future Minimum Payments, Due in Three Years	[6]	967		884	[5]
Operating Leases, Future Minimum Payments, Due in Four Years	[6]	967		967	[5]
Operating Leases, Future Minimum Payments, Due in Five Years	[6]	967		967	[5]
Operating Leases, Future Minimum Payments, Due Thereafter	[6]	1,691		2,658	[5]
Operating Leases, Future Minimum Payments Due	[6]	6,332		7,188	[5]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Receivable with Imputed Interest, Discount	[6]	921
Operating Lease, Liability	[6]	5,411
General and Administrative Expense		$ 909
Operating Lease, Weighted Average Discount Rate, Percent		4.62%
sublease [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Operating Leases, Income Statement, Lease Revenue		$ (23,492)
Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lessee, Operating Lease, Term of Contract		30 years
Maximum [Member] | Ground Lease Arrangement [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lessee, Operating Lease, Term of Contract		47 years
Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lessee, Operating Lease, Term of Contract		1 year
Minimum [Member] | Ground Lease Arrangement [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lessee, Operating Lease, Term of Contract		1 year
Ground Lease Arrangement [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Straight-Line Rent Receivable		$ 24,454		$ 0		$ 0
Ground Lease Arrangement [Member] | sub-lessor [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Straight-Line Rent Receivable		$ 24,569

[1] (1) At December 31, 2019, includes $24.6 million in sub-lessor straight-line rent receivables. Sub-lessor straight-line receivables relate to the Company's operating ground leases. The Company's tenants, who are generally sub-tenants under these ground leases, are responsible for paying the rent under these leases. See Note 16 for information related to the Company's leases.

[2] Included in rental revenue

[3] Balances as of December 31, 2018 are prior to the adoption of Topic 842.

[4] Included in property operating expense

[5] Balances as of December 31, 2018 are prior to the adoption of Topic 842.

[6] Included in general and administrative expense.