Summary of Significant Accounting Policies Supplemental Disclosures Related to Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental cash flow information
Total interest costs incurred	$ 54,636	$ 53,736	$ 55,418
Interest capitalized	628	1,488	1,570
Interest expense	54,008	52,248	53,848
Cash paid for interest, net of amounts capitalized	51,975	52,632	47,473
Cash paid for income taxes	971	462	461
Supplemental schedule of noncash investing and financing activities
Accounts payable and accrued liabilities for construction in progress	25,413	14,440	6,863
Accrued leasing commissions	3,345	5,229	1,694
Reduction to capital for prepaid equity financing costs	0	241	0
Building recorded in termination of ground lease	$ 4,518	$ 0	$ 0