Merger With Tier REIT, Inc. (Pro Forma Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Business Combinations [Abstract]
Revenues	$ 182,114	$ 172,894	$ 365,382	$ 346,442
Net income (loss)	63,386	14,696	87,813	(10,470)
Net income (loss) available to common stockholders	$ 62,503	$ 14,466	$ 86,643	$ (10,416)