CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ 4,163	$ (37,471)	$ (46,577)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation	78,396	84,482	85,175
Amortization of in-place lease assets	44,795	54,439	68,477
Amortization of deferred leasing costs	1,522	986	375
Amortization (including accelerated write-off) of deferred financing costs	7,598	5,648	6,693
Accretion of mortgage premiums and discounts on borrowings	(3,816)	(3,790)	(4,096)
Discount accretion and premium amortization on investments, net	0	0	(25)
Amortization (accretion) of market lease and other intangibles, net	(7,372)	(15,518)	(5,173)
Equity-based compensation	12,717	5,266	128
Vesting and conversion of Class B Units	0	15,786	0
Mark-to-market adjustments	0	(72)	(130)
Gain on sale of real estate investments	(23,690)	(31,776)	(15,128)
Impairment of real estate investments	2,432	21,080	25,049
Payments of prepayment costs on mortgages	4,491	4,224	0
Changes in assets and liabilities:
Straight-line rent receivable	(9,521)	(9,596)	(7,840)
Straight-line rent payable	1,196	95	96
Prepaid expenses and other assets	(3,208)	(4,086)	2,575
Accounts payable and accrued expenses	(1,458)	1,694	(7,780)
Deferred rent and other liabilities	(2,675)	3,646	(9,355)
Net cash provided by operating activities	105,570	95,037	92,464
Cash flows from investing activities:
Proceeds from the settlement of CMBS	0	0	17,200
Capital expenditures	(13,652)	(10,426)	(8,917)
Acquisitions of investments in real estate and other assets	(428,939)	(241,772)	(149,337)
Proceeds from sale of real estate investments	34,813	66,455	190,801
Deposits	2,952	(2,472)	(565)
Cash paid in merger transaction	0	0	(94,504)
Cash acquired in merger transaction	0	0	26,163
Net cash used in investing activities	(404,826)	(188,215)	(19,159)
Cash flows from financing activities:
Proceeds from mortgage notes payable	286,930	29,887	267,350
Payments on mortgage notes payable	(69,144)	(47,197)	(21,841)
Proceeds from credit facility	233,000	324,700	85,000
Payments on credit facility	(224,553)	(95,000)	(294,000)
Payments of financing costs	(10,778)	(7,031)	(4,948)
Payments of prepayment costs on mortgages	(4,491)	(4,224)	0
Common stock repurchases	(274)	(20,531)	(29,058)
Distributions on LTIP Units and Class A Units	(694)	(225)	0
Distributions paid	(117,140)	(104,824)	(87,659)
Dividends paid on preferred stock	(3,948)	0	0
Proceeds from issuance of common stock, net	31,601	0	0
Proceeds from issuance of preferred stock, net	168,956	0	0
Net cash provided by (used in) financing activities	289,465	75,555	(85,156)
Net change in cash and cash equivalents	(9,791)	(17,623)	(11,851)
Cash, cash equivalents and restricted cash, beginning of period	109,631	127,254	139,105
Cash, cash equivalents and restricted cash, end of period	99,840	109,631	127,254
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	81,898	91,451	107,666
Restricted cash	17,942	18,180	19,588
Supplemental Disclosures:
Cash paid for interest	72,826	63,839	57,017
Cash paid for income taxes	217	1,100	827
Non-Cash Investing and Financing Activities:
Accrued Preferred Stock offering costs	27	0	0
Preferred dividend declared but not yet paid	3,300	80
Equity issued in the merger transaction	0	0	921,930
Credit facility assumed or used to acquire investments in real estate	0	0	304,000
Proceeds from real estate sales used to pay off related mortgage notes payable	94,940	90,038	103,041
Mortgage notes payable released in connection with disposition of real estate	(94,940)	(90,038)	(103,041)
Mortgage notes payable assumed or used to acquire investments in real estate	0	0	127,651
Premiums on assumed mortgage notes payable	0	0	4,143
Common stock issued through distribution reinvestment plan	0	23,248	55,853
Accrued capital expenditures (payable)	355	341	933
Preferred Stock | Dividend Declared
Non-Cash Investing and Financing Activities:
Preferred dividend declared but not yet paid	$ 3,300	$ 0	$ 0