Organization - Summary of Redeemable Noncontrolling Interest (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Redeemable Noncontrolling Interest, Equity, Fair Value [Abstract]
Beginning balance noncontrolling redeemable Operating Partnership Units			$ 13,622
Issuance of Operating Partnership Units			2,148
Net income attributable to noncontrolling interests - consolidated joint venture	$ 144	$ 125	250	$ 228	$ 526	$ 469	$ 513
Distributions			(251)	$ (271)
Adjustment to redemption value			(27)
Ending balance noncontrolling redeemable Operating Partnership Units	$ 15,742		$ 15,742		$ 13,622