Stock-Based Compensation (Detail) - Summary Of Changes In CSEs Outstanding - Common stock equivalents (CSEs)	3 Months Ended
	Mar. 31, 2017 $ / 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, 2016 (in shares) | shares	107,338
Granted (in shares) | shares	1,592
Converted to common shares upon grant (in shares) | shares	1,161
Outstanding at March 31, 2017 (in shares) | shares	107,769
Per Share Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at December 31, 2016 (in dollars per share) | $ / shares	$ 20.74
Granted (in dollars per share) | $ / shares	108.95
Converted to common shares upon grant (in dollars per share) | $ / shares	108.95
Outstanding at March 31, 2017 (in dollars per share) | $ / shares	$ 21.09