Commitments and Contingencies	3 Months Ended
Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Other than as noted below, there have been no material changes during the period covered by this Form 10-Q in the status of the legal proceedings disclosed in Note 10 to the consolidated financial statements in Part II of our 2017 10-K. Investigations and Litigation Apollo and Parks Township In January 2010, Michelle McMunn, Cara D. Steele and Yvonne Sue Robinson filed suit against Babcock & Wilcox Power Generation Group, Inc. ("B&W PGG"), Babcock & Wilcox Technical Services Group, Inc., formerly known as B&W Nuclear Environmental Services, Inc. and now known as BWXT Technical Services Group, Inc. (the "BWXT Parties") and Atlantic Richfield Company ("ARCO") in the U.S. District Court for the Western District of Pennsylvania. Since January 2010, additional suits were filed by additional plaintiffs and there are currently 17 lawsuits pending in the U.S. District Court for the Western District of Pennsylvania (the "Trial Court") against the BWXT Parties and ARCO, including the most recent lawsuits filed in June and October 2015. In total, the suits involve approximately 107 primary claimants. The primary claimants allege, among other things, personal injuries and property damage as a result of alleged releases of radioactive material relating to the operation, remediation and/or decommissioning of two former nuclear fuel processing facilities located in the Borough of Apollo and Parks Township, Pennsylvania (collectively, the "Apollo and Parks Litigation"). Those facilities previously were owned by Nuclear Materials and Equipment Company, a former subsidiary of ARCO ("NUMEC"), which was acquired by B&W PGG. The plaintiffs in the Apollo and Parks Litigation seek compensatory and punitive damages, and in November 2014 delivered a demand of $125.0 million for the settlement of all then-filed actions. While we consider the likelihood of the plaintiffs' recovery to be remote, solely on the basis of this demand we estimate the range of a possible loss at between $0.0 million and $125.0 million. In connection with the spin-off of our former Power Generation business, we agreed to indemnify B&W PGG and its affiliates for any losses arising from the Apollo and Parks Litigation pursuant to the Master Separation Agreement. Between May 2015 and March 2016, the presiding judge in the Apollo and Parks Litigation granted the BWXT Parties' motions to dismiss or motions for summary judgment in all 17 of the existing lawsuits. Accordingly, all current claims in the Apollo and Parks Litigation have been dismissed by the Trial Court. All plaintiffs filed notices of appeal, and the appeals were consolidated in the U.S. Court of Appeals for the Third Circuit (the "Court of Appeals"). On August 23, 2017, the Court of Appeals affirmed the rulings of the Trial Court, dismissing all claims against the BWXT Parties and other defendants in the cases. Plaintiffs filed a notice of petition for rehearing, which was denied by the Court of Appeals on September 21, 2017. The plaintiffs filed a writ of certiorari for review by the U.S. Supreme Court on December 20, 2017. On February 20, 2018, the U.S. Supreme Court denied plaintiffs' petition for writ of certiorari making the Court of Appeals decision affirming the dismissal of all 17 lawsuits final. At the time of ARCO's sale of NUMEC stock to B&W PGG, B&W PGG received an indemnity and hold harmless agreement from ARCO, which has been assigned to BWXT and its affiliates, with respect to claims and liabilities arising prior to or as a result of conduct or events predating the acquisition. The ARCO indemnity remains applicable should any future claims similar in nature to the Apollo and Parks Litigation be made, although no assurance can be given that the indemnity will be available or sufficient in the event of liability, if any.

COMMITMENTS AND CONTINGENCIES

Other than as noted below, there have been no material changes during the period covered by this Form 10-Q in the status of the legal proceedings disclosed in Note 10 to the consolidated financial statements in Part II of our 2017 10-K.

Investigations and Litigation

Apollo and Parks Township

In January 2010, Michelle McMunn, Cara D. Steele and Yvonne Sue Robinson filed suit against Babcock & Wilcox Power Generation Group, Inc. ("B&W PGG"), Babcock & Wilcox Technical Services Group, Inc., formerly known as B&W Nuclear Environmental Services, Inc. and now known as BWXT Technical Services Group, Inc. (the "BWXT Parties") and Atlantic Richfield Company ("ARCO") in the U.S. District Court for the Western District of Pennsylvania. Since January 2010, additional suits were filed by additional plaintiffs and there are currently 17 lawsuits pending in the U.S. District Court for the Western District of Pennsylvania (the "Trial Court") against the BWXT Parties and ARCO, including the most recent lawsuits filed in June and October 2015. In total, the suits involve approximately 107 primary claimants. The primary claimants allege, among other things, personal injuries and property damage as a result of alleged releases of radioactive material relating to the operation, remediation and/or decommissioning of two former nuclear fuel processing facilities located in the Borough of Apollo and Parks Township, Pennsylvania (collectively, the "Apollo and Parks Litigation"). Those facilities previously were owned by Nuclear Materials and Equipment Company, a former subsidiary of ARCO ("NUMEC"), which was acquired by B&W PGG. The plaintiffs in the Apollo and Parks Litigation seek compensatory and punitive damages, and in November 2014 delivered a demand of $125.0 million for the settlement of all then-filed actions. While we consider the likelihood of the plaintiffs' recovery to be remote, solely on the basis of this demand we estimate the range of a possible loss at between $0.0 million and $125.0 million. In connection with the spin-off of our former Power Generation business, we agreed to indemnify B&W PGG and its affiliates for any losses arising from the Apollo and Parks Litigation pursuant to the Master Separation Agreement.

Between May 2015 and March 2016, the presiding judge in the Apollo and Parks Litigation granted the BWXT Parties' motions to dismiss or motions for summary judgment in all 17 of the existing lawsuits. Accordingly, all current claims in the Apollo and Parks Litigation have been dismissed by the Trial Court. All plaintiffs filed notices of appeal, and the appeals were consolidated in the U.S. Court of Appeals for the Third Circuit (the "Court of Appeals"). On August 23, 2017, the Court of Appeals affirmed the rulings of the Trial Court, dismissing all claims against the BWXT Parties and other defendants in the cases. Plaintiffs filed a notice of petition for rehearing, which was denied by the Court of Appeals on September 21, 2017. The plaintiffs filed a writ of certiorari for review by the U.S. Supreme Court on December 20, 2017. On February 20, 2018, the U.S. Supreme Court denied plaintiffs' petition for writ of certiorari making the Court of Appeals decision affirming the dismissal of all 17 lawsuits final.

At the time of ARCO's sale of NUMEC stock to B&W PGG, B&W PGG received an indemnity and hold harmless agreement from ARCO, which has been assigned to BWXT and its affiliates, with respect to claims and liabilities arising prior to or as a result of conduct or events predating the acquisition.

The ARCO indemnity remains applicable should any future claims similar in nature to the Apollo and Parks Litigation be made, although no assurance can be given that the indemnity will be available or sufficient in the event of liability, if any.