New Accounting Standards - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect adjustment to retained earnings	$ 3,189
ASU 2016-16
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect adjustment to retained earnings	3,200
Cumulative effect adjustment to retained earnings, net impact of increase in deferred tax assets	2,600
Cumulative effect adjustment to retained earnings, net impact of decrease in deferred tax charge in other assets	$ (5,800)