Shareholders' Equity - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017 USD ($)
Equity [Abstract]
Share repurchase program, authorized amount	$ 100,000,000
Stock repurchase program, term (in years)	3 years
Stock repurchase program, expiration date	2019-12
Stock repurchase program, remaining authorized repurchase amount	$ 99,000,000