Summary of Significant Accounting Policies - Research and Engineering (Details) - In Process Research and Development - Two T D Drilling - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets
Intangible Assets	$ 47.7	$ 32.5	$ 21.7
Transfer of research and development expenses to completed technology	$ 0.0	$ 0.0	$ 0.0

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration