Supplemental Disclosure to Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Information [Abstract]
Write-off of fully depreciated/amortized property and deferred costs	$ 19,833	$ 19,002
Write-off of depreciated/amortized property and deferred costs due to sale	8,989	33,857
Redemption of noncontrolling interests - common units	27	0
Unrealized gain (loss) on cash flow hedge	275	(1,795)
Changes in accrued development capital expenditures	13,124	2,383
Capitalized equity-based compensation	$ 739	$ 808