Property and Equipment, Field Equipment and Deferred Cost of Revenues - Additional Information (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Deferred costs, accumulated amortization	$ 109.5	$ 106.3
Property And Equipment Excluding Field Equipment
Property, Plant and Equipment [Line Items]
Accumulated depreciation	60.5	56.8
Field Equipment
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 52.9	$ 51.6

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.14)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant