Status of Stock Options (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Shares
Outstanding | shares	5,817,116
Vested and expected to vest | shares	5,680,016
Vested | shares	3,310,206
Weighted-Average Exercise Price Per Share
Outstanding | $ / shares	$ 25.26
Vested and expected to vest | $ / shares	25.11
Vested | $ / shares	$ 20.29
Remaining Contractual Life
Outstanding	6 years 10 months 24 days
Vested and expected to vest	6 years 10 months 24 days
Vested	5 years 8 months 12 days
Aggregate Intrinsic Value
Outstanding | $	$ 22,295
Vested and expected to vest | $	22,267
Vested | $	$ 21,966