Stock-Based Compensation - Summary of Restricted Common Shares (Detail) - Restricted Stock And Units [Member]	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested Number, Beginning Balance (in shares) | shares	378,746
Granted (in shares) | shares	153,818
Vested (in shares) | shares	(133,564)
Forfeited (in shares) | shares	(27,441)
Non-vested Number, Ending Balance (in shares) | shares	371,559
Non-vested Weighted Average Grant Date Fair Value, Beginning Balance (in dollars per share) | $ / shares	$ 53.56
Granted (in dollars per share) | $ / shares	70.09
Vested (in dollars per share) | $ / shares	41.79
Forfeited (in dollars per share) | $ / shares	62.39
Non-vested Weighted Average Grant Date Fair Value, Ending Balance (in dollars per share) | $ / shares	$ 63.98