Stock-Based Compensation (Detail) - Summary Of Changes In CSEs Outstanding - Common stock equivalents (CSEs)	9 Months Ended
	Sep. 30, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base fee percentage (up to)	50.00%
Common Stock Equivalents (CSEs) [Roll Forward]
Outstanding at December 31, 2015 (in shares) | shares	105,664
Granted (in shares) | shares	5,332
Converted to common shares upon grant (in shares) | shares	(4,127)
Outstanding at September 30, 2016 (in shares) | shares	106,869
Per Share Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at December 31, 2015 (in dollars per share) | $ / shares	$ 19.57
Granted (in dollars per share) | $ / shares	91.96
Converted to common shares upon grant (in dollars per share) | $ / shares	91.96
Outstanding at September 30, 2016 (in dollars per share) | $ / shares	$ 20.39