Fair Value Measurement - Amount of Gains and Losses from Changes in Fair Value Included in Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair Value Inputs Assets Quantitative Information [Line Items]
Change in fair value			$ 2,205	$ 1,836
Construction [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Change in fair value	$ 556	$ 1,421	2,205	1,836
Total change in fair value	$ 556	$ 1,421	$ 2,205	$ 1,836