Revenue Revenue	12 Months Ended
Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Contract Balances The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables and deferred revenue and advance payments from customers on the Consolidated Balance Sheets. Contract assets and liabilities are reported on a contract-by-contract basis. The Company had no material deferred contract costs recorded on the Consolidated Balance Sheet as of December 31, 2018. Contract assets: The Company recognizes unbilled receivables as contract assets when the Company has rights to consideration for work completed but has not yet billed at the reporting date. Unbilled receivables are included within accounts receivable, net on the Consolidated Balance Sheets. The balance of unbilled receivables as of December 31, 2018 and at the date of adoption of ASC 606 were $10.5 million and $14.1 million, respectively. Contract Liabilities: The Company records contract liabilities when cash payments are received or due in advance of the Company's performance. Contract liabilities include deferred revenue and advance payments from customers. Contract liabilities are classified as either current or long-term in the Consolidated Balance Sheets based on the timing of when the Company expects to recognize revenue. As of December 31, 2018 and at the date of the adoption of ASC 606, the Company's contract liability balances totaled $66.4 million and $60.1 million, respectively. These balances included amounts classified as long-term as of December 31, 2018 and at the date of the adoption of ASC 606 of $14.0 million and $13.8 million, respectively, which are included within pension and other long-term liabilities in the accompanying Consolidated Balance Sheets. Approximately $42.2 million of revenue recognized during the twelve month period ended December 31, 2018 was included in the combined opening contract liability balances adjusted for the ASC 606 adoption impacts. Remaining Performance Obligations Remaining performance obligations related to ASC 606 represent the aggregate transaction price allocated to performance obligations with an original contract term greater than one year which are fully or partially unsatisfied at the end of the period. While the remaining performance obligation disclosure is similar in concept to backlog, the definition of remaining performance obligations excludes contracts that provide the customer with the right to cancel or terminate for convenience with no substantial penalty, even if historical experience indicates the likelihood of cancellation or termination is remote. The Company has elected to exclude contracts with customers with an original term of one year or less from remaining performance obligations while these contracts are included within backlog. As of December 31, 2018, the aggregate amount of the transaction price allocated to remaining performance obligations was approximately $154.4 million. The Company expects to recognize revenue on approximately 85 percent of the remaining performance obligations over the next twelve months, and the remainder recognized thereafter.

Revenue

Contract Balances

The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables and deferred revenue and advance payments from customers on the Consolidated Balance Sheets. Contract assets and liabilities are reported on a contract-by-contract basis. The Company had no material deferred contract costs recorded on the Consolidated Balance Sheet as of December 31, 2018.

Contract assets: The Company recognizes unbilled receivables as contract assets when the Company has rights to consideration for work completed but has not yet billed at the reporting date. Unbilled receivables are included within accounts receivable, net on the Consolidated Balance Sheets. The balance of unbilled receivables as of December 31, 2018 and at the date of adoption of ASC 606 were $10.5 million and $14.1 million, respectively.

Contract Liabilities: The Company records contract liabilities when cash payments are received or due in advance of the Company's performance. Contract liabilities include deferred revenue and advance payments from customers. Contract liabilities are classified as either current or long-term in the Consolidated Balance Sheets based on the timing of when the Company expects to recognize revenue. As of December 31, 2018 and at the date of the adoption of ASC 606, the Company's contract liability balances totaled $66.4 million and $60.1 million, respectively. These balances included amounts classified as long-term as of December 31, 2018 and at the date of the adoption of ASC 606 of $14.0 million and $13.8 million, respectively, which are included within pension and other long-term liabilities in the accompanying Consolidated Balance Sheets. Approximately $42.2 million of revenue recognized during the twelve month period ended December 31, 2018 was included in the combined opening contract liability balances adjusted for the ASC 606 adoption impacts.

Remaining Performance Obligations

Remaining performance obligations related to ASC 606 represent the aggregate transaction price allocated to performance obligations with an original contract term greater than one year which are fully or partially unsatisfied at the end of the period. While the remaining performance obligation disclosure is similar in concept to backlog, the definition of remaining performance obligations excludes contracts that provide the customer with the right to cancel or terminate for convenience with no substantial penalty, even if historical experience indicates the likelihood of cancellation or termination is remote. The Company has elected to exclude contracts with customers with an original term of one year or less from remaining performance obligations while these contracts are included within backlog.

As of December 31, 2018, the aggregate amount of the transaction price allocated to remaining performance obligations was approximately $154.4 million. The Company expects to recognize revenue on approximately 85 percent of the remaining performance obligations over the next twelve months, and the remainder recognized thereafter.