Stockholders' Equity - Other (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended	15 Months Ended
	Mar. 31, 2021 USD ($) item $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Mar. 31, 2021 USD ($) item $ / shares shares	May 16, 2016 shares
Stockholders' Equity
Shares available for issuance	300		300
Stock option and restricted stock
Stock-based compensation
Stock-based compensation expense (in dollars) | $			$ 1,300
Restricted Stock
Stock-based compensation
Unrecognized compensation cost related to unvested restricted stock (in dollars) | $	$ 5,000		$ 5,000
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)	499
Granted (in shares)	433
Vested (in shares)	(242)
Outstanding at the end of the period (in shares)	690	499	690
Weighted-average grant date fair value
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 11.26
Granted (in dollars per share) | $ / shares	11.72
Vested (in dollars per share) | $ / shares	11.65
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 11.42	$ 11.26	$ 11.42
Stock options
Stock-based compensation
Unrecognized compensation cost related to unvested stock options (in dollars) | $	$ 4,400		$ 4,400
Weighted-average periods over which unrecognized compensation cost recognized	2 years 1 month 6 days
Estimated forfeitures (as a percent)	1.50%		1.50%
Valuation assumptions
Dividend yield (as a percent)	0.00%
Number of shares
Outstanding at the beginning of the period (in shares)	3,935
Granted (in shares)	495
Exercised (in shares)	(50)
Outstanding at the end of the period (in shares)	4,380	3,935	4,380
Vested at the end of the period (in shares)	3,102		3,102
Exercisable at the end of the period (in shares)	3,102		3,102
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 11.69
Granted (in dollars per share) | $ / shares	11.87
Exercised (in dollars per share) | $ / shares	10.20
Outstanding at the end of the period (in dollars per share) | $ / shares	11.68	$ 11.69	$ 11.68
Vested at the end of the period (in dollars per share) | $ / shares	11.59		11.59
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 11.59		$ 11.59
Weighted-average remaining contractual term
Outstanding	5 years 4 months 24 days	5 years 1 month 6 days
Granted	6 years
Vested at the end of the period	4 years
Exercisable at the end of the period	4 years
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars) | $	$ 291
Outstanding at the end of the period (in dollars) | $	2,079	$ 291	$ 2,079
Vested at the end of the period (in dollars) | $	1,970		1,970
Exercisable at the end of the period (in dollars) | $	$ 1,970		$ 1,970
Weighted-average grant date fair value of options granted (in dollars per share) | $ / shares	$ 4.64
Weighted average grant date fair value of options granted | $ / shares	$ 4.64
Number of options granted	495
Performance-based Stock Option
Number of shares
Unvested options	500		500
Time Based Restricted Stock Awards and Stock Option
Stockholders' Equity
Number of equal annual installments for vesting of awards | item	3		3
Time Based Restricted Stock Awards and Stock Option | Black Scholes Pricing Model
Valuation assumptions
Weighted-average expected term (years)	6 years	6 years
Time Based Restricted Stock Awards and Stock Option | Minimum | Black Scholes Pricing Model
Valuation assumptions
Risk-free interest rate (as a percent)	0.97%	0.42%
Volatility (as a percent)	37.30%	44.20%
Time Based Restricted Stock Awards and Stock Option | Maximum | Black Scholes Pricing Model
Valuation assumptions
Risk-free interest rate (as a percent)	1.08%	0.50%
Volatility (as a percent)	39.80%	46.10%
Time Based Restricted Stock
Aggregate intrinsic value
Vesting period	3 years
Common Class A
Stockholders' Equity
Shares authorized for issuance				7,200