Employees Retirement Plans - Pension expense (Details) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2019
USD ($)
item
|
Dec. 31, 2018
USD ($)
|
Dec. 31, 2017
USD ($)
|
|
| Employee Retirement Plans | |||
| Number of regional multi-employer pension plans in which the entity participates | item | 43 | ||
| Defined contribution plans | $ 10,015 | $ 7,595 | $ 4,089 |
| Multi-employer plans | 13,241 | 11,224 | 8,677 |
| Total expense related to participation in retirement plans | $ 23,256 | $ 18,819 | $ 12,766 |
| X | ||||||||||
- Definition Amount of expense related to multiemployer retirement plans. No definition available.
|
| X | ||||||||||
- Definition Represents the number of regional multi-employer pension plans in which the entity participates. No definition available.
|
| X | ||||||||||
- Definition The amount of expense related to Company's participation in retirement plans. No definition available.
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Amount of cost for defined contribution plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|