Accounts Receivable and Major Customers - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Customer	Dec. 31, 2012 Customer
Sales Revenue | Customer Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of major customers	3	4
Revenues, major customers	$ 181.7	$ 182.0
Concentration risk, percentage	42.00%	59.00%
Sales Revenue | Customer Concentration Risk | Major Customer 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	70.4	60.1
Concentration risk, percentage	16.00%	19.00%
Sales Revenue | Customer Concentration Risk | Major Customer 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	55.9	46.7
Concentration risk, percentage	13.00%	15.00%
Sales Revenue | Customer Concentration Risk | Major Customer 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	55.4	41.5
Concentration risk, percentage	13.00%	13.00%
Sales Revenue | Customer Concentration Risk | Major Customer 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers		33.8
Concentration risk, percentage		11.00%
Accounts Receivable | Credit Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	37.00%	49.00%
Accounts receivable, major customers	$ 34.8	$ 21.6