Accounts Receivable and Major Customers - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) Customer	Dec. 31, 2014 USD ($) Customer
Sales Revenue | Customer Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of major customers | Customer	3	3
Revenues, major customers	$ 168.9	$ 258.7
Concentration risk, percentage	64.00%	50.00%
Sales Revenue | Customer Concentration Risk | Major Customer 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	$ 74.5	$ 113.6
Concentration risk, percentage	28.00%	22.00%
Sales Revenue | Customer Concentration Risk | Major Customer 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	$ 63.5	$ 80.1
Concentration risk, percentage	24.00%	16.00%
Sales Revenue | Customer Concentration Risk | Major Customer 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	$ 30.9	$ 65.0
Concentration risk, percentage	12.00%	12.00%
Accounts Receivable | Credit Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	90.00%	58.00%
Accounts receivable, major customers	$ 21.1	$ 36.1