Commitments and Contingencies (Details) |
Mar. 31, 2018
USD ($)
letter_of_credit
|
|---|---|
| Debt Instrument [Line Items] | |
| Number of letters of credit provided as collateral | letter_of_credit | 2 |
| Standby Letters of Credit | |
| Debt Instrument [Line Items] | |
| Current borrowing capacity | $ 18,000,000 |
| Credit Facility | Revolving Credit Facility | |
| Debt Instrument [Line Items] | |
| Line of credit facility | 75,000,000.0 |
| Unused portion of facility | 60,000,000 |
| Credit Facility | Letter of Credit Facility | |
| Debt Instrument [Line Items] | |
| Line of credit facility | 40,000,000.0 |
| Credit Facility | Swingline Facility | |
| Debt Instrument [Line Items] | |
| Line of credit facility | 10,000,000.0 |
| Collateral for Workers' Compensation Obligation | Line of Credit Facility | |
| Debt Instrument [Line Items] | |
| Line of credit facility | 5,000,000.0 |
| Unused portion of facility | $ 3,000,000 |