Summary of Share-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock option awards	$ 1,704	$ 1,598	$ 3,123
Common, deferred, restricted and restricted unit awards	2,836	2,029	2,658
Share-based compensation	4,540	3,627	5,781
Allocated Share-based Compensation Expense	3,829	8,147	9,897
Liability-classified awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	$ (711)	$ 4,520	$ 4,116