Stockholders' Equity - Other (Details) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
	Dec. 27, 2019 $ / shares shares	Dec. 31, 2019 USD ($) D item $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares
Stockholders' Equity
Shares available for issuance		1,200
Stock option and restricted stock
Stock-based compensation
Stock-based compensation expense (in dollars) | $		$ 4,800	$ 3,900
Stock options
Stock-based compensation
Unrecognized compensation cost related to unvested stock options (in dollars) | $		$ 4,200
Weighted-average periods over which unrecognized compensation cost recognized		2 years 2 months 12 days
Estimated forfeitures (as a percent)		1.50%
Valuation assumptions
Dividend yield (as a percent)		0.00%
Number of shares
Outstanding at the beginning of the period (in shares)		2,910	2,898
Granted (in shares)		1,025	109
Exercised (in shares)		(60)	(67)
Forfeited (in shares)			(24)
Expired (in shares)		(20)	(6)
Outstanding at the end of the period (in shares)		3,855	2,910	2,898
Vested at the end of the period (in shares)		2,732
Exercisable at the end of the period (in shares)		2,732
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share) | $ / shares		$ 11.62	$ 11.62
Granted (in dollars per share) | $ / shares		12.06	12.84
Exercised (in dollars per share) | $ / shares		11.63	13.38
Forfeited (in dollars per share) | $ / shares			12.30
Expired (in dollars per share) | $ / shares		13.64	12.10
Outstanding at the end of the period (in dollars per share) | $ / shares		11.72	$ 11.62	$ 11.62
Vested at the end of the period (in dollars per share) | $ / shares		11.57
Exercisable at the end of the period (in dollars per share) | $ / shares		$ 11.57
Weighted-average remaining contractual term
Outstanding		6 years 1 month 6 days	5 years 7 months 6 days	6 years 6 months
Granted		6 years	6 years
Vested at the end of the period		4 years 7 months 6 days
Exercisable at the end of the period		4 years 7 months 6 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars) | $		$ 2,806	$ 1,738
Outstanding at the end of the period (in dollars) | $		12,101	$ 2,806	$ 1,738
Vested at the end of the period (in dollars) | $		9,016
Exercisable at the end of the period (in dollars) | $		$ 9,016
Weighted-average grant date fair value of options granted (in dollars per share) | $ / shares		$ 4.93	$ 5.49
Restricted Stock
Stock-based compensation
Unrecognized compensation cost related to unvested restricted stock (in dollars) | $		$ 5,200
Weighted-average periods over which unrecognized compensation cost recognized		2 years 1 month 6 days
Number of shares
Outstanding at the beginning of the period (in shares)		370	504
Granted (in shares)		581	93
Vested (in shares)		(352)	(218)
Forfeited (in shares)		(7)	(9)
Outstanding at the end of the period (in shares)		592	370	504
Weighted-average grant date fair value
Outstanding at the beginning of the period (in dollars per share) | $ / shares		$ 9.86	$ 10.23
Granted (in dollars per share) | $ / shares		12.37	11.85
Vested (in dollars per share) | $ / shares		9.78	11.49
Forfeited (in dollars per share) | $ / shares		14.55	11.85
Outstanding at the end of the period (in dollars per share) | $ / shares		$ 12.32	$ 9.86	$ 10.23
Time Based Restricted Stock Awards and Stock Option
Stockholders' Equity
Number of equal annual installments for vesting of awards | item		3
Time Based Stock Option | Black Scholes Pricing Model
Valuation assumptions
Risk-free interest rate, minimum (as a percent)			2.70%
Risk-free interest rate, maximum (as a percent)			3.00%
Risk-free interest rate (as a percent)		1.60%
Volatility, minimum (as a percent)			39.00%
Volatility, maximum (as a percent)			41.00%
Volatility (as a percent)		40.30%
Weighted-average expected term (years)		6 years	6 years
Time Based Restricted Stock
Aggregate intrinsic value
Vesting period		3 years
Event Based Stock Option
Aggregate intrinsic value
Vested options	300
Event Based Restricted Stock
Aggregate intrinsic value
Vested options	200
Common Class A
Stockholders' Equity
Shares authorized for issuance		7,200
Common Class A | Event Based Stock Option
Stockholders' Equity
Closing price per share to be attained for vesting of awards to begin (in dollars per share) | $ / shares	$ 15.00
Number of trading days on which the closing price per share should attain the specified price per share for vesting of awards to begin | D		10
Common Class A | Event Based Restricted Stock
Stockholders' Equity
Closing price per share to be attained for vesting of awards to begin (in dollars per share) | $ / shares	$ 15.00
Number of trading days on which the closing price per share should attain the specified price per share for vesting of awards to begin | D		10