Contracts with Customers (Notes)

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Long-term Contracts or Programs Disclosure [Text Block]

Contracts with Customers

Unbilled receivables increased from $8,194 at December 31, 2017 to $9,822 at March 31, 2018, primarily driven by revenue recognized at BDS in excess of billings.

Advances and progress billings increased from $48,042 at December 31, 2017 to $49,955 during the three months ended March 31, 2018, primarily driven by advances on orders received in excess of revenue recognized at BCA.

Revenues recognized during the three months ended March 31, 2018 and 2017 from amounts recorded as Advances and progress billings at the beginning of each year were $6,453 and $5,411.