Cash and Marketable Securities (Narrative) (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Cash and Marketable Securities [Abstract]
Impairment charges due to other than temporary declines in the value of certain investments	$ 0	$ 0
Equity Securities, Unrealized Gain (Loss)	0	(1,000,000)
Minority interests in several strategic investments	5,000,000	5,000,000
Increase in minority interests in several strategic investments	$ 1,000,000	$ 1,000,000

Increase In Investments and Other Noncurrent Assets

No definition available.

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Namespace Prefix:	serv_
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- Definition

Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117546-209714

+ Details

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- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562

+ Details

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- References

No definition available.

+ Details

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- Definition

Amount of investments, and noncurrent assets classified as other.

+ References

No definition available.

+ Details

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Period Type:	instant