Stock Based Compensation Plan (Details) - USD ($) $ / shares in Units, $ in Millions | 6 Months Ended |
Jun. 30, 2016 | Jun. 30, 2015 |
Weighted-Average Award Price [Roll Forward] | | |
Period of restrictions over awards | 4 years | |
Compensation expense | $ 2.2 | $ 2.2 |
Total compensation cost related to unvested equity awards | $ 6.1 | |
Weighted-average period of recognition of cost | 2 years 4 months 24 days | |
Restricted Stock Award [Member] | | |
Shares or Units and Rights [Roll Forward] | | |
Outstanding, beginning balance (in shares) | 344,490 | |
Granted (in shares) | 205,640 | |
Restrictions lapsed or exercised (in shares) | (140,864) | |
Forfeited (in shares) | (4,450) | |
Outstanding, ending balance (in shares) | 404,816 | |
Exercisable, ending balance (in shares) | 0 | |
Awards expected to vest (in shares) | 408,886 | |
Weighted-Average Award Price [Roll Forward] | | |
Outstanding, beginning balance (in dollars per share) | $ 22.87 | |
Granted (in dollars per share) | 18.80 | |
Restrictions lapsed or exercised (in dollars per share) | 18.29 | |
Forfeited (in dollars per share) | 19.29 | |
Outstanding, ending balance (in dollars per share) | 21.65 | |
Exercisable, ending balance (in dollars per share) | 0 | |
Awards expected to vest (in dollars per share) | $ 21.62 | |
Vesting period | 3 years | |
Aggregate intrinsic value of outstanding awards | $ 7.3 | |
Stock-Settled Appreciation Rights [Member] | | |
Shares or Units and Rights [Roll Forward] | | |
Outstanding, beginning balance (in shares) | 100,875 | |
Granted (in shares) | 0 | |
Restrictions lapsed or exercised (in shares) | 0 | |
Forfeited (in shares) | 0 | |
Outstanding, ending balance (in shares) | 100,875 | |
Exercisable, ending balance (in shares) | 74,875 | |
Awards expected to vest (in shares) | 100,875 | |
Weighted-Average Award Price [Roll Forward] | | |
Outstanding, beginning balance (in dollars per share) | $ 18.14 | |
Granted (in dollars per share) | 0 | |
Restrictions lapsed or exercised (in dollars per share) | 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) | $ 18.14 | |
Aggregate intrinsic value of vested awards | $ 0 | |
Aggregate intrinsic value of outstanding awards | $ 0 | |
Performance Shares [Member] | | |
Shares or Units and Rights [Roll Forward] | | |
Granted (in shares) | 58,138 | |
Performance Shares [Member] | Maximum [Member] | | |
Weighted-Average Award Price [Roll Forward] | | |
Vesting period | 4 years | |
Performance Shares [Member] | Minimum [Member] | | |
Weighted-Average Award Price [Roll Forward] | | |
Vesting period | 1 year | |