Schedule of Principal Payments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
2016	$ 5,000
2017	10,000
2018	10,000
2019	15,000
2020	824,000
Thereafter	600,000
Total debt	$ 1,464,000	$ 1,200,000