Summary of Significant Accounting Policies Supplemental Disclosures Related to Consolidated Statements of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental cash flow information
Total interest costs incurred	$ 58,455	$ 60,133	$ 58,074
Interest capitalized	5,490	2,113	746
Interest expense	52,965	58,020	57,328
Cash paid for interest, net of amounts capitalized (including discontinued operations)	48,032	54,345	55,349
Cash paid for income taxes	404	901	1,239
Supplemental schedule of noncash investing and financing activities
Accounts payable and accrued liabilities for construction in progress	9,908	5,001	4,944
Accrued leasing commissions	763	1,385	(782)
Accrued placement fees for senior guaranteed notes payable	750	0	0
Reduction to capital for prepaid equity financing costs	$ 40	$ 437	$ 0