Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Loss Carryforwards [Line Items]
Income taxes paid	$ 110,191,000	$ 80,622,000	$ 75,403,000
Range of expiration dates for portions of net operating loss carryforwards	2014 through 2033
Accrued interest and penalties related to uncertain tax positions	121,000	79,000
Total amount of unrecognized tax benefits that would affect effective tax rate	391,000	294,000	806,000	656,000
Beginning of Range [Member] | Colorado [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2008
Beginning of Range [Member] | OREGON [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2009
Beginning of Range [Member] | MICHIGAN [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2009
End of Range [Member] | Colorado [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2011
End of Range [Member] | OREGON [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2012
End of Range [Member] | MICHIGAN [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2011
Federal Income Tax [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	22,135,000
Federal Income Tax [Member] | Beginning of Range [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2011
Federal Income Tax [Member] | End of Range [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2013
State Income Tax [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 94,561,000
State Income Tax [Member] | Beginning of Range [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2008
State Income Tax [Member] | End of Range [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2013
United Kingdom [Member] | Beginning of Range [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2012
United Kingdom [Member] | End of Range [Member]
Operating Loss Carryforwards [Line Items]
Fiscal years open for audit	2013