Backlog	12 Months Ended
Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Backlog	23. Backlog DBMG’s backlog was $503.5 million ($441.1 million under contracts or purchase orders and $62.4 million under letters of intent) at December 31, 2016. DBMG’s backlog increases as contract commitments, letters of intent, notices to proceed and purchase orders are obtained, decreases as revenues are recognized and increases or decreases to reflect modifications in the work to be performed under the contracts, notices to proceed, letters of intent or purchase orders. DBMG’s backlog can be significantly affected by the receipt, or loss, of individual contracts. Approximately $296.4 million, representing 58.9% of DBMG’s backlog at December 31, 2016, was attributable to five contracts, letters of intent, notices to proceed or purchase orders. If one or more of these large contracts or other commitments are terminated or their scope reduced, DBMG’s backlog could decrease substantially. DBMG's backlog at December 31, 2015 was $380.8 million ($252.7 million under contracts or purchase orders and $128.1 million under letters of intent). At December 31, 2014, its backlog was $357.0 million ($305.3 million under contracts or purchase orders and $51.7 million under letters of intent).

Backlog

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

23. Backlog

DBMG’s backlog was $503.5 million ($441.1 million under contracts or purchase orders and $62.4 million under letters of intent) at December 31, 2016. DBMG’s backlog increases as contract commitments, letters of intent, notices to proceed and purchase orders are obtained, decreases as revenues are recognized and increases or decreases to reflect modifications in the work to be performed under the contracts, notices to proceed, letters of intent or purchase orders. DBMG’s backlog can be significantly affected by the receipt, or loss, of individual contracts. Approximately $296.4 million, representing 58.9% of DBMG’s backlog at December 31, 2016, was attributable to five contracts, letters of intent, notices to proceed or purchase orders. If one or more of these large contracts or other commitments are terminated or their scope reduced, DBMG’s backlog could decrease substantially.

DBMG's backlog at December 31, 2015 was $380.8 million ($252.7 million under contracts or purchase orders and $128.1 million under letters of intent).

At December 31, 2014, its backlog was $357.0 million ($305.3 million under contracts or purchase orders and $51.7 million under letters of intent).