Commitments and Other Contingencies (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2008 sqft
Operating Leased Assets [Line Items]
operating lease future payments, 2015	$ 3,308,000
operating lease future payments, 2016	3,111,000
operating lease future payments, 2016	3,101,000
operating lease future payments, 2018	2,165,000
operating lease future payments, 2019	571,000
operating lease future payments, thereafter	2,284,000
Office Facilities And Other Equipment [Member]
Operating Leased Assets [Line Items]
Lease expense	2,617,000	2,374,000	2,115,000
Ground Water Lease [Member]
Operating Leased Assets [Line Items]
Remaining years of timber lease	3 years
Timber land area taken on lease	20,000
Remaining contractual obligation of groundwater lease	1,514,000
Corporate Headquarters [Member]
Operating Leased Assets [Line Items]
Net Rentable Area				32,000
Remaining contractual obligation of groundwater lease	5,632,000
Other Office Locations [Member]
Operating Leased Assets [Line Items]
Remaining contractual obligation of groundwater lease	$ 6,262,000
Other Office Locations [Member] | Texas [Member]
Operating Leased Assets [Line Items]
Net Rentable Area	21,000
Other Office Locations [Member] | COLORADO
Operating Leased Assets [Line Items]
Net Rentable Area	10,000