Overview and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	6 Months Ended
	Apr. 30, 2017	Jun. 30, 2017	Jun. 30, 2016
Subsidiary, Sale of Stock [Line Items]
Number of shares issued from public offering (in shares)	5,808,080
Proceeds from public offering of common stock, net of commissions	$ 270,200	$ 270,250	$ 0
Public Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued from public offering (in shares)	5,050,505
Offer price (in usd per share)	$ 49.50
Proceeds from public offering of common stock, net of commissions	$ 235,000
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Number of shares issued from public offering (in shares)	757,575
Proceeds from public offering of common stock, net of commissions	$ 35,200