Stockholder's Equity - Initial public offering (Details) $ / shares in Units, $ in Thousands		9 Months Ended
	Jul. 20, 2017 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) shares
Class of Stock [Line Items]
Proceeds from Initial Public Offering (IPO) of Class A Shares | $		$ 104,010
Repayments of Notes Payable | $		$ 55,960
Common stock, shares outstanding		13,222,583
Pet, LLC and Subsidiaries (the "Company")
Class of Stock [Line Items]
Number of shares purchased		3,556,666
Pet, LLC and Subsidiaries (the "Company") | IPO
Class of Stock [Line Items]
Repayments of Notes Payable | $	$ 55,960
Class A
Class of Stock [Line Items]
Common Stock, Shares, Issued		13,222,583
Common stock, shares outstanding		13,222,583
Class A | IPO
Class of Stock [Line Items]
Common Stock, Shares, Issued	7,187,500
Share Price | $ / shares	$ 16.00
Proceeds from Initial Public Offering (IPO) of Class A Shares | $	$ 106,950
Class A | Holdco | IPO
Class of Stock [Line Items]
Number of shares purchased	3,556,666
Class B
Class of Stock [Line Items]
Common Stock, Shares, Issued		8,268,188
Common stock, shares outstanding		8,268,188
Certain Executives | Class B
Class of Stock [Line Items]
Number of shares purchased	133,334
Amended Holdco LLC Agreement
Class of Stock [Line Items]
Common stock, shares outstanding		21,490,771
Amended Holdco LLC Agreement | Holdco
Class of Stock [Line Items]
Number of shares purchased		9,532,583
Amended Holdco LLC Agreement | Class A
Class of Stock [Line Items]
Stockholders' Equity Note, Stock Split, Conversion Ratio	1
Amended Holdco LLC Agreement | Class B
Class of Stock [Line Items]
Stockholders' Equity Note, Stock Split, Conversion Ratio	1