Sale of Commercial Business - Summary of Charges Related to Restructuring Activities (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Restructuring Cost And Reserve [Line Items]
Accrued Restructuring Expenses at Dec 31, 2016	$ 774
Accrued Restructuring Expenses at Mar 31, 2017	581
Commercial Business [Member]
Restructuring Cost And Reserve [Line Items]
Expenses	5,265
Accrued Restructuring Expenses at Mar 31, 2017	5,265
Commercial Business [Member] | Severance Benefits and Related Costs [Member]
Restructuring Cost And Reserve [Line Items]
Expenses	5,265
Accrued Restructuring Expenses at Mar 31, 2017	$ 5,265