Stock-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Thousands | 6 Months Ended | 12 Months Ended |
Jun. 30, 2015 | Jun. 30, 2014 | Dec. 31, 2014 |
Restricted and performance-based stock, weighted average grant date fair value per share [Roll Forward] | | | |
Compensation expense, gross | $ 2,927 | $ 2,397 | |
Stock Options [Member] | | | |
Options, shares [Roll Forward] | | | |
Outstanding, beginning of period (in shares) | 9,875 | | |
Expired (in shares) | 0 | | |
Exercised (in shares) | (9,875) | | |
Forfeited, other (in shares) | 0 | | |
Outstanding, end of period (in shares) | 0 | | 9,875 |
Options exercisable, end of period (in shares) | 0 | | |
Options, weighted average exercise price [Roll Forward] | | | |
Outstanding, beginning of period (in dollars per share) | $ 10.99 | | |
Expired (in dollars per share) | 0 | | |
Exercised (in dollars per share) | 10.99 | | |
Forfeited, other (in dollars per share) | 0 | | |
Outstanding, end of period (in dollars per share) | 0 | | $ 10.99 |
Options exercisable, end of period (in dollars per share) | $ 0 | | |
Options, additional disclosures [Abstract] | | | |
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2 | | | 4 months 24 days |
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2 | | | 4 months 24 days |
Options exercisable, weighted average remaining contractual term, end of period | | | |
Total intrinsic value of options exercised | $ 300 | | |
Options granted (in shares) | 0 | | |
Performance-based Shares [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Measuring period for performance-based shares | 3 years | | |
Award vesting rights | Selected executives and other key personnel are granted performance awards whose vesting is contingent upon meeting various performance measures with a retention feature. Performance-based shares are subject to a three-year measuring period and the achievement of performance targets and, depending upon the achievement of such performance targets, they may become vested on the third anniversary of the date of grant. | | |
Restricted Shares [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Award vesting rights | Restricted shares granted to employees become fully vested upon the third anniversary of the date of grant; and for selected key executives, certain additional restricted share grants vest 25% upon the attainment of age 60, 25% upon the attainment of age 63 and become fully vested upon the attainment of age 65. Restricted shares granted to directors become fully vested upon the first anniversary of the date of grant. | | |
Restricted Shares [Member] | Employees [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Estimated forfeitures (in hundredths) | 5.00% | | |
Restricted Shares [Member] | Executives [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Estimated forfeitures (in hundredths) | 0.00% | | |
Restricted Shares [Member] | Directors [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Estimated forfeitures (in hundredths) | 0.00% | | |
Restricted Shares [Member] | Age 60 [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Vesting percentage (in hundredths) | 25.00% | | |
Restricted Shares [Member] | Age 63 [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Vesting percentage (in hundredths) | 25.00% | | |
Restricted Shares [Member] | Age65 [Member] | | | |
Restricted and Performance Stock Grants [Abstract] | | | |
Vesting percentage (in hundredths) | 100.00% | | |
Restricted and Performance-based shares [Member] | | | |
Restricted and performance-based stock, shares [Roll Forward] | | | |
Beginning of period (in shares) | 749,018 | | |
Granted (in shares) | 7,000 | | |
Vested (in shares) | (44,293) | | |
Forfeited (in shares) | (2,675) | | |
End of period (in shares) | 709,050 | | 749,018 |
Restricted and performance-based stock, weighted average grant date fair value per share [Roll Forward] | | | |
Beginning of period (in dollars per share) | $ 24.62 | | |
Granted (in dollars per share) | 35.07 | | |
Vested (in dollars per share) | 34.47 | | |
Forfeited (in dollars per share) | 25 | | |
End of period (in dollars per share) | $ 24.10 | | $ 24.62 |
Compensation expense, gross | $ 2,500 | 2,000 | |
Compensation expense, net of tax | 1,600 | $ 1,300 | |
Unamortized compensation expense | $ 9,700 | | |
Restricted and Performance-based shares [Member] | Employees [Member] | | | |
Restricted and performance-based stock, weighted average grant date fair value per share [Roll Forward] | | | |
Weighted average period of recognition for unrecognized compensation expense | 4 years 9 months 18 days | | |
Restricted and Performance-based shares [Member] | Directors [Member] | | | |
Restricted and performance-based stock, weighted average grant date fair value per share [Roll Forward] | | | |
Weighted average period of recognition for unrecognized compensation expense | 9 months 18 days | | |