CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities:
Net income	$ 261,183,000	$ 3,310,000	$ 1,374,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	141,102,000	158,847,000	164,289,000
Impairment charges on real estate	8,706,000	0	0
Equity in loss (income) of unconsolidated entities	1,443,000	(2,088,000)	1,000
Deferred rents	(6,224,000)	(9,063,000)	(12,402,000)
Loss due to property damage	0	0	8,401,000
Bad debt expense	0	1,230,000	1,863,000
Amortization of above- and below-market leases, net	(3,515,000)	(5,350,000)	(6,710,000)
Amortization of deferred financing costs	5,385,000	6,356,000	4,952,000
Loss from extinguishment of debt	2,229,000	225,000	766,000
Unrealized losses (gains) on derivative instruments	35,664,000	(11,192,000)	(10,509,000)
Gain on sale of real estate	(327,211,000)	(11,942,000)	0
Changes in operating assets and liabilities:
Rents and other receivables	(10,600,000)	(11,230,000)	(5,220,000)
Prepaid expenses and other assets	(32,947,000)	(21,476,000)	(25,126,000)
Accounts payable and accrued liabilities	(933,000)	1,236,000	5,373,000
Other liabilities	(7,114,000)	1,154,000	(2,731,000)
Due to affiliates	3,460,000	910,000	118,000
Net cash provided by operating activities	70,628,000	100,927,000	124,439,000
Cash Flows from Investing Activities:
Improvements to real estate	(79,931,000)	(88,721,000)	(81,949,000)
Proceeds from sale of real estate, net	931,489,000	41,649,000	0
Proceeds from the sale of equity securities	16,186,000	0	0
Payments for construction in progress	(21,706,000)	(34,229,000)	(45,734,000)
Investment in an unconsolidated entity	0	(426,000)	(33,708,000)
Payments of post-closing acquisition costs	1,014,000	0	0
Purchase of joint venture partner's equity interest	0	(28,268,000)	0
Escrow deposits for tenant improvements	972,000	1,111,000	(2,084,000)
Insurance proceeds received for property damage	867,000	4,629,000	0
Net cash provided by (used in) investing activities	846,863,000	(104,255,000)	(163,475,000)
Cash Flows from Financing Activities:
Proceeds from notes payable	377,589,000	507,909,000	942,184,000
Principal payments on notes payable	(1,107,369,000)	(335,243,000)	(778,670,000)
Payments of deferred financing costs	(2,609,000)	(3,243,000)	(11,206,000)
Payments to redeem common stock	(100,996,000)	(96,064,000)	(61,871,000)
Payments of prepaid other offering costs	(264,000)	0	0
Payments of other offering costs	(16,000)	(15,000)	(12,000)
Distributions paid to common stockholders	(110,592,000)	(59,464,000)	(57,971,000)
Net cash (used in) provided by financing activities	(944,257,000)	13,880,000	32,454,000
Net (decrease) increase in cash, cash equivalents and restricted cash	(26,766,000)	10,552,000	(6,582,000)
Cash, cash equivalents and restricted cash, beginning of period	76,038,000	65,486,000	72,068,000
Cash, cash equivalents and restricted cash, end of period	49,272,000	76,038,000	65,486,000
Supplemental Disclosure of Cash Flow Information:
Interest paid, net of capitalized interest of $1,711, $2,832 and $2,433 for the years ended December 31, 2019, 2018 and 2017, respectively	75,471,000	76,107,000	58,472,000
Supplemental Disclosure of Noncash Investing and Financing Activities:
Equity securities received in connection with the portfolio sale	271,000,000	0	0
Distributions payable	9,392,000	9,801,000	9,982,000
Distributions paid to common stockholders through common stock issuances pursuant to the dividend reinvestment plan	51,704,000	56,136,000	59,785,000
Redeemable common stock payable	0	31,647,000	18,869,000
Accrued improvements to real estate	26,310,000	17,426,000	24,731,000
Construction in progress payable	2,144,000	5,148,000	4,360,000
Acquisition fee related to construction in progress due to affiliate	1,133,000	916,000	566,000
Acquisition fee on unconsolidated joint venture due to affiliate	0	0	290,000
Real estate consolidated in connection with joint venture purchase	0	132,100,000	0
Note payable assumed in connection with joint venture purchase	0	66,570,000	0
Liabilities assumed in connection with joint venture purchase	$ 0	$ 3,173,000	$ 0