Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) vesting_type $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved shares of common stock for possible future issuance	3,400,000
Number of award vesting types | vesting_type	2
Weighted-average grant date fair value of options issued (in dollars per share) | $ / shares	$ 2.36	$ 3.29	$ 4.25
Total intrinsic value of options exercised | $	$ 0.1	$ 0.9	$ 0.9
Cash liability for performance-based units | $	$ 0.0
Employee stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options issued (in shares)	0	46,000
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	0	0	0
Options vested (in shares)	1,000	4,000	0
Options forfeited in period (in shares)	8,000	106,000	9,000
Stock-based compensation expense | $	$ (0.2)	$ 0.2	$ 0.0
Options, nonvested, number of shares (in shares)	335,000
Total unrecognized compensation cost related to non-vested stock options granted | $	$ 0.1
Weighted-average period for recognition (in years)	1 year 10 months 24 days
Service Based Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	8,000	27,000	31,000
Options forfeited in period (in shares)	80,000	22,000	8,000
Stock-based compensation expense | $	$ 0.1	$ 0.2	$ 0.3
Vesting period (in years)	4 years
Expiration term (in years)	8 years
Total unrecognized compensation cost related to non-vested stock options granted | $	$ 0.1
Weighted-average period for recognition (in years)	2 years 1 month 6 days
Market Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	0
Options vested (in shares)	0
Options forfeited in period (in shares)	0	136,000	91,000
Stock-based compensation expense | $		$ 0.0	$ 0.0
Expiration term (in years)	8 years
Performance Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options issued (in shares)		226,000	153,000
Vested (in shares)	1,000	1,000	7,000
Forfeited (in shares)	6,000	49,000	5,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options issued (in shares)	163,000	130,000	81,000
Vesting period (in years)	4 years
Forfeited (in shares)	3,000	12,000	2,000
Restricted Stock [Member] | Non Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options issued (in shares)	22,000	10,000	9,000
Stock-based compensation expense | $	$ 0.3	$ 0.1	$ 0.1
Deferred Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options issued (in shares)	54,000	47,000	44,000
Percentage of shares vested in lieu of directors fees at the grant date	100.00%
Portion of Director fees matched to deferred stock units	25.00%
Vesting period of deferred stock (in years)	1 year
Restricted Stock Unit And Performance Stock Unit And Deferred Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense | $	$ 1.3	$ 1.9	$ 1.3
Vested (in shares)	135,000	89,000
Forfeited (in shares)	10,000	61,000
Compensation cost not yet recognized | $	$ 5.1
Total fair value of stock-based compensation vested | $	$ 1.6	$ 1.2	$ 1.1
2014 Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	4,100,000