Stockholder's Equity - Reorganization and amendment (Details) $ / shares in Units, $ in Millions	Jul. 20, 2017 USD ($) Vote class $ / shares shares	Dec. 31, 2017 $ / shares shares	Jul. 19, 2017 shares
Class of Stock [Line Items]
Ownership interest in Holdco	61.50%	61.50%
Ownership interest by continuing LLC owners	38.50%	38.50%
Pet, LLC and Subsidiaries (the "Company")
Class of Stock [Line Items]
Number of shares purchased		3,556,666
Sponsor Corps
Class of Stock [Line Items]
LLC interests held			7,523,839
Continuing LLC Owners
Class of Stock [Line Items]
Common unit issued in exchange of shares (in shares)	133,334
Cash paid | $	$ 2.1
Continuing LLC Owners | Pet, LLC and Subsidiaries (the "Company")
Class of Stock [Line Items]
Number of shares purchased		133,334
Class A
Class of Stock [Line Items]
Common Stock, Shares, Issued		13,222,583
Common stock authorized		125,000,000
Common stock, par value | $ / shares		$ 0.001
Class A | IPO
Class of Stock [Line Items]
Common Stock, Shares, Issued	7,187,500
Class A | IPO | Holdco
Class of Stock [Line Items]
Number of shares purchased	3,556,666
Class A | Sponsor Corps | IPO
Class of Stock [Line Items]
Common Stock, Shares, Issued	5,615,981
Class B common stock
Class of Stock [Line Items]
Common Stock, Shares, Issued		8,268,188
Common stock authorized		8,401,521
Common stock, par value | $ / shares		$ 0.001
Amended Holdco LLC Agreement
Class of Stock [Line Items]
Ownership interest in Holdco		61.50%
Blank check preferred stock, authorized	12,500,000
Number of classes of directors | class	3
Staggered service term	3 years
Number of vote per share | Vote	1
Amended Holdco LLC Agreement | Holdco
Class of Stock [Line Items]
Number of shares purchased		9,532,583
Amended Holdco LLC Agreement | Sponsor Corps
Class of Stock [Line Items]
Preference notes payable | $	$ 30.5
Amended Holdco LLC Agreement | Continuing LLC Owners
Class of Stock [Line Items]
Preference notes payable | $	$ 25.4
Common unit issued in exchange of shares (in shares)	1,589,642
Amended Holdco LLC Agreement | Class A
Class of Stock [Line Items]
Common stock authorized	125,000,000
Common stock, par value | $ / shares	$ 0.001
Conversion ratio	1
Amended Holdco LLC Agreement | Class A | Certain Employee Owners
Class of Stock [Line Items]
Common unit issued in exchange of shares (in shares)	419,102
Amended Holdco LLC Agreement | Class B common stock
Class of Stock [Line Items]
Common stock authorized	8,401,521
Common stock, par value | $ / shares	$ 0.001
Conversion ratio	1
Cancellation ratio	1