Stock Based Compensation Plan (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended |
Mar. 31, 2018 | Mar. 31, 2017 |
Additional Disclosures [Abstract] | | | |
Stock based compensation expense | | $ 1.6 | $ 1.3 |
Total compensation cost related to unvested equity awards | | $ 7.8 | |
Weighted-average period of recognition of cost | | 2 years 6 months | |
Service-Based Restricted Stock Awards [Member] | | | |
Shares or Units and Rights [Roll Forward] | | | |
Outstanding, beginning balance (in shares) | | 254,490 | |
Granted/Issued (in shares) | | 116,035 | |
Awards vested or rights exercised (in shares) | [1] | 0 | |
Forfeited (in shares) | | (400) | |
Outstanding, ending balance (in shares) | | 370,125 | |
Exercisable, ending balance (in shares) | | 0 | |
Awards expected to vest (in shares) | | 370,125 | |
Weighted-Average Award Price [Roll Forward] | | | |
Outstanding, beginning balance (in dollars per share) | | $ 21.88 | |
Granted/Issued (in dollars per share) | | 22.95 | |
Awards vested or rights exercised (in dollars per share) | [1] | 0 | |
Forfeited (in dollars per share) | | 22.38 | |
Outstanding, ending balance (in dollars per share) | | 22.21 | |
Exercisable, ending balance (in dollars per share) | | 0 | |
Awards expected to vest (in dollars per share) | | $ 22.21 | |
Additional Disclosures [Abstract] | | | |
Aggregate intrinsic value of outstanding awards | | $ 7.5 | |
Service-Based Restricted Stock Awards [Member] | Minimum [Member] | | | |
Additional Disclosures [Abstract] | | | |
Vesting period of awards | | 1 year | |
Service-Based Restricted Stock Awards [Member] | Maximum [Member] | | | |
Additional Disclosures [Abstract] | | | |
Vesting period of awards | | 4 years | |
Performance-Based Restricted Stock Awards [Member] | | | |
Shares or Units and Rights [Roll Forward] | | | |
Outstanding, beginning balance (in shares) | | 179,774 | |
Granted/Issued (in shares) | | 103,940 | |
Awards vested or rights exercised (in shares) | [1] | (46,269) | |
Forfeited (in shares) | | (7,033) | |
Outstanding, ending balance (in shares) | | 230,412 | |
Exercisable, ending balance (in shares) | | 0 | |
Awards expected to vest (in shares) | | 214,481 | |
Weighted-Average Award Price [Roll Forward] | | | |
Outstanding, beginning balance (in dollars per share) | | $ 21.42 | |
Granted/Issued (in dollars per share) | | 22.95 | |
Awards vested or rights exercised (in dollars per share) | [1] | 20.35 | |
Forfeited (in dollars per share) | | 0 | |
Outstanding, ending balance (in dollars per share) | | 21.60 | |
Exercisable, ending balance (in dollars per share) | | 0 | |
Awards expected to vest (in dollars per share) | | $ 21.58 | |
Additional Disclosures [Abstract] | | | |
Vesting period of awards | | 3 years | |
Fair value of vested shares | | $ 1.1 | |
Aggregate intrinsic value of outstanding awards | | $ 4.6 | |
Stock-Settled Appreciation Rights [Member] | | | |
Shares or Units and Rights [Roll Forward] | | | |
Outstanding, beginning balance (in shares) | | 57,000 | |
Granted/Issued (in shares) | | 0 | |
Awards vested or rights exercised (in shares) | [1] | 0 | |
Forfeited (in shares) | | 0 | |
Outstanding, ending balance (in shares) | | 57,000 | |
Exercisable, ending balance (in shares) | | 57,000 | |
Awards expected to vest (in shares) | | 0 | |
Weighted-Average Award Price [Roll Forward] | | | |
Outstanding, beginning balance (in dollars per share) | | $ 18.14 | |
Granted/Issued (in dollars per share) | | 0 | |
Awards vested or rights exercised (in dollars per share) | [1] | 0 | |
Forfeited (in dollars per share) | | 0 | |
Outstanding, ending balance (in dollars per share) | | 18.14 | |
Exercisable, ending balance (in dollars per share) | | 18.14 | |
Awards expected to vest (in dollars per share) | | $ 0 | |
Additional Disclosures [Abstract] | | | |
Aggregate intrinsic value of outstanding awards | | $ 0.1 | |
Aggregate intrinsic value of vested awards | | $ 0.1 | |
| |
[1] | Includes shares repurchased from employees for employee's tax liability. | |