Contracts with Customers (Notes)

6 Months Ended

Jun. 30, 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 $9,868 at June 30, 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 $50,970 at June 30, 2018, primarily driven by advances on orders received in excess of revenue recognized at BCA.

In the six and three months ended June 30, 2018, we recognized revenue of $12,757 and $6,304 related to our Advances and progress billings at January 1, 2017. In the six and three months ended June 30, 2017, we recognized revenue of $11,687 and $6,276 related to our Advances and progress billings at January 1, 2016.