Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value transfers between level 1 to level 2	$ 0	$ 0
Fair value transfers between level 2 to level 1	0	0
Fair value transfers into level 3	0	0
Fair value transfers out of level 3	0	0
Level II [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Severance pay assets	$ 5,100,000	$ 4,500,000