Leases (Tables) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2019

Mar. 31, 2018

Lessor, Lease, Description [Line Items]

Operating lease expense under the Company's ground and office leases was as follows, including straight lined rent expense and variable lease expenses such as CPI increases, performance based rent and reimbursements of landlord costs:



		Three months ended March 31,
		2019
Operating lease expense
Ground leases	$	3,673
Office leases		1,042
Total fixed operating lease expense	$	4,715
Variable lease expense
Ground leases	$	428
Office leases		143
Total variable lease expense	$	571
Total Lease Expense	$	5,286
Cash paid for amounts included in the measurement of operating lease liabilities
Operating cash flows from operating leases	$	3,692

Operating Lease, Lease Income [Table Text Block]

The following table provides a disaggregation of lease income recognized during the three months ended March 31, 2019, under ASC Topic 842, Leases, as either fixed or variable lease income based on the criteria specified in ASC 842:



		Three months ended March 31,
		2019
Operating lease income
Fixed and in-substance fixed lease income	$	201,878
Variable lease income		62,835
Other lease related income, net
Above/below market rent amortization		13,454
Uncollectible amounts in lease income		(864	)
Total lease income	$	277,303

Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block]

Future minimum rents under non-cancelable operating leases as of March 31, 2019 and December 31, 2018, excluding variable lease payments, are as follows:



		Future Minimum Rents as of (in thousands)
Year Ending December 31,		March 31, 2019			December 31, 2018
2019	$	578,963	⁽¹	⁾	761,151
2020		713,553			693,848
2021		629,638			608,587
2022		537,753			516,369
2023		437,109			414,424
Thereafter		1,778,839			1,691,203
Total	$	4,675,855			4,685,582
⁽¹⁾ The future minimum rental income for 2019 as of March 31, 2019 includes amounts due between April 1, 2019 and December 31, 2019.

Operating Lease, Expense

$ 5,286

$ 4,200

Lessee, Operating Lease, Liability, Maturity [Table Text Block]

The following table summarizes the undiscounted future cash flows by year attributable to the operating lease liabilities under ground and office leases as of March 31, 2019, and provides a reconciliation to the Lease liability included in the accompanying Consolidated Balance Sheets:



		Lease liabilities (in thousands)
Year Ending December 31,		Ground Leases		Office Leases		Total
2019 ⁽¹⁾	$	8,004		3,807		11,811
2020		10,706		4,976		15,682
2021		10,674		3,863		14,537
2022		10,698		2,893		13,591
2023		10,914		2,188		13,102
Thereafter		598,327		5,955		604,282
Total undiscounted lease liabilities	$	649,323		23,682		673,005
Present value discount		(445,324	)	(2,559	)	(447,883	)
Lease liabilities		203,999		21,123		225,122
Weighted average discount rate		5.2	%	4.0	%
Weighted average remaining term		49.9 years		5.9 years

⁽¹⁾ The undiscounted lease liability maturities shown for 2019 are as of March 31, 2019, and includes amounts due between April 1, 2019 and December 31, 2019.

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

The following table summarizes the future obligations under non-cancelable operating leases, excluding unexercised renewal options, as of December 31, 2018:



		Future Lease Obligations (in thousands)
Year Ending December 31,		Ground Leases	Office Leases	Total Future Lease Obligations
2019	$	10,672	4,405	15,077
2020		10,439	4,294	14,733
2021		10,344	3,549	13,893
2022		10,258	2,893	13,151
2023		10,369	2,189	12,558
Thereafter		461,762	5,944	467,706
Total	$	513,844	23,274	537,118