Retirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | $ 9 | $ 9 | ||
| Interest cost | 966 | 954 | ||
| Expected return on plan assets | (1,384) | (1,416) | ||
| Amortization of net loss | 543 | 486 | ||
| Net periodic benefit cost | $ 45 | $ 11 | 134 | 33 |
| Hourly Employees’ Pension Plan | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 6 | 6 | ||
| Interest cost | 300 | 303 | ||
| Expected return on plan assets | (486) | (495) | ||
| Amortization of net loss | 213 | 186 | ||
| Net periodic benefit cost | 33 | 0 | ||
| Employees’ Retirement Plan | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 3 | 3 | ||
| Interest cost | 666 | 651 | ||
| Expected return on plan assets | (898) | (921) | ||
| Amortization of net loss | 330 | 300 | ||
| Net periodic benefit cost | $ 101 | $ 33 | ||