Stock-Based Compensation - Summary of Stock Option Activity (Detail) - Stock Options [Member]	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Summary Of Stock Option Activities [Line Items]
Options Outstanding, Beginning balance, Shares | shares	825,561
Options Outstanding, Exercised | shares	(121,026)
Options Outstanding, Expired or cancelled | shares	(83,182)
Options Outstanding, Forfeited | shares	(40,652)
Options Outstanding, Ending balance, Shares | shares	580,701
Options Exercisable, Ending balance, Shares | shares	567,025
Options Outstanding, Beginning balance, Weighted Average Exercise Price | $ / shares	$ 7.30
Weighted Average Exercise Price, Exercised | $ / shares	7.11
Weighted Average Exercise Price, Expired or Cancelled | $ / shares	8.35
Weighted Average Exercise Price, Forfeited | $ / shares	6.70
Options Outstanding, Ending balance, Weighted Average Exercise Price | $ / shares	7.23
Options Outstanding, Exercisable at End of Year, Weighted Average Exercise Price | $ / shares	$ 7.27