Merger With Tier REIT, Inc. (Pro Forma Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Combinations [Abstract]
Revenues	$ 188,323	$ 176,711	$ 555,324	$ 521,945
Net income	21,740	44,218	110,188	30,829
Net income available to common stockholders	$ 21,410	$ 43,689	$ 108,724	$ 30,466