Commitments and Other Contingencies (Detail) ft² in Thousands, a in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) a ft²	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Operating Leased Assets [Line Items]
Operating lease future payments, 2017	$ 2,267
Operating lease future payments, 2018	1,593
Operating lease future payments, 2019	298
Operating lease future payments, 2020	182
Operating lease future payments, 2021	62
Operating lease future payments, thereafter	0
Office Facilities And Other Equipment
Operating Leased Assets [Line Items]
Lease expense	$ 1,923	$ 3,872	$ 2,617
Ground Water Lease
Operating Leased Assets [Line Items]
Remaining years of timber lease	1 year
Timber land area taken on lease | a	20
Remaining contractual obligation	$ 494
Corporate Headquarters
Operating Leased Assets [Line Items]
Remaining contractual obligation	$ 1,983
Corporate Headquarters | Texas
Operating Leased Assets [Line Items]
Net rentable area | ft²	22
Other Office Locations
Operating Leased Assets [Line Items]
Remaining contractual obligation	$ 1,925