Summary of Significant Accounting Policies Supplemental Disclosures Related to Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental cash flow information
Total interest costs incurred	$ 54,829	$ 58,455	$ 60,133
Interest capitalized	7,569	5,490	2,113
Interest expense	47,260	52,965	58,020
Cash paid for interest, net of amounts capitalized	42,691	48,032	54,345
Cash paid for income taxes	633	404	901
Supplemental schedule of noncash investing and financing activities
Accounts payable and accrued liabilities for construction in progress	(14,733)	9,908	5,001
Accrued leasing commissions	(901)	763	1,385
Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction	0	750	0
Reduction to capital for prepaid equity financing costs	$ 54	$ 40	$ 437