Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) vote Joint_Venture property $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($)	Feb. 19, 2020 USD ($)
Significant Accounting Policies [Line Items]
Number of real estate properties | property	4
Number of joint ventures | Joint_Venture	3
Intangible Lease Liabilities (Below-Market In-Place Leases)	$ 84,292,000	$ 94,852,000
Amortization of Intangible Lease Origination Costs and In-Place Lease Valuation included in amortization expense	62,413,000	48,940,000	$ 58,467,000
Amortization of Above-Market and Below-Market In-Place Lease intangibles as a net increase to rental revenues	8,322,000	7,615,000	6,575,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Total	80,979,000	77,676,000
Below Market Lease, Net, Amortization Income, Fiscal Maturity [Abstract]
2020	8,304,000
2021	7,901,000
2022	6,421,000
2023	4,616,000
2024	1,706,000
Thereafter	3,778,000
Total	$ 32,726,000
Weighted-Average Amortization Period (in years)	5 years
Significant Accounting Policies [Abstract]
Provision for doubtful accounts		91,000	350,000
Capitalized internal leasing costs		300,000	300,000
Amortization of deferred lease costs	$ 50,300,000	43,600,000	50,800,000
Amortization of lease incentive	3,200,000	2,600,000	4,800,000
Amortization of fair value adjustments	500,000	500,000	500,000
Amortization of debt discount	200,000	200,000	200,000
Amortization of deferred financing costs and fair market value adjustments on notes payable	$ 2,400,000	$ 2,400,000	2,800,000
Shares-in-trust, shares authorized | shares	150,000,000	150,000,000
Preferred stock, shares authorized | shares	100,000,000	100,000,000
Common stock, shares authorized | shares	750,000,000	750,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Number of votes for each share of common stock | vote	1
Stock repurchase program, remaining authorized repurchase amount		$ 74,100,000
At-the-market offerings, maximum amount	$ 250,000,000
Dividend reinvestment plan, shareholders discount	2.00%
Income tax expense (benefit)	$ 160,000	(97,000)	13,000
Rental and tenant reimbursement revenue	511,905,000	504,410,000	553,264,000
General and administrative	37,895,000	29,713,000	29,319,000
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits
Significant Accounting Policies [Abstract]
Assets held as trading securities	600,000	400,000
Above-Market In-place Lease Assets
Significant Accounting Policies [Line Items]
Intangible lease assets	2,082,000	7,620,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2020	423,000
2021	367,000
2022	272,000
2023	97,000
2024	64,000
Thereafter	0
Total	$ 1,223,000
Weighted-Average Amortization Period (in years)	3 years
In-Place Lease Valuation
Significant Accounting Policies [Line Items]
Intangible lease assets	$ 157,101,000	157,447,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2020	22,397,000
2021	18,650,000
2022	13,950,000
2023	9,383,000
2024	4,861,000
Thereafter	10,515,000
Total	$ 79,756,000
Weighted-Average Amortization Period (in years)	5 years
Intangible Lease Origination Costs
Significant Accounting Policies [Line Items]
Intangible lease assets	$ 256,627,000	241,516,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2020	34,267,000
2021	30,112,000
2022	23,341,000
2023	16,055,000
2024	9,576,000
Thereafter	22,957,000
Total	$ 136,308,000
Weighted-Average Amortization Period (in years)	6 years
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Significant Accounting Policies [Abstract]
Rental income			19,200,000
General and administrative			1,800,000
Restatement Adjustment | Accounting Standards Update 2016-02
Significant Accounting Policies [Abstract]
Rental income		(411,700,000)	(455,100,000)
Tenant reimbursements		$ (92,700,000)	$ (98,200,000)
Subsequent Event
Significant Accounting Policies [Abstract]
Stock repurchase program, authorized amount				$ 200,000,000
Building
Significant Accounting Policies [Line Items]
Useful life	40 years
Building improvements | Minimum
Significant Accounting Policies [Line Items]
Useful life	5 years
Building improvements | Maximum
Significant Accounting Policies [Line Items]
Useful life	25 years
Land improvements | Minimum
Significant Accounting Policies [Line Items]
Useful life	20 years
Land improvements | Maximum
Significant Accounting Policies [Line Items]
Useful life	25 years
Furniture, fixtures, and equipment | Minimum
Significant Accounting Policies [Line Items]
Useful life	3 years
Furniture, fixtures, and equipment | Maximum
Significant Accounting Policies [Line Items]
Useful life	10 years
1201 Eye Street NW Associates LLC and 1225 Eye Street, NW Associates LLC
Significant Accounting Policies [Line Items]
Number of joint ventures | Joint_Venture	2