SCHEDULE III Investment property reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Beginning balance	$ 4,573,522	$ 3,363,917
Community and land acquisitions, including immediate improvements	1,822,564	1,214,482	$ 798,827
Community expansion and development	47,958	28,660	22,195
Improvements, other	113,803	195,439	173,989
Asset impairment	0	0	(1,870)
Dispositions and other	(61,508)	(228,976)	(118,343)
Ending balance	$ 6,496,339	$ 4,573,522	$ 2,489,119