For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Significant Service Provider Partners (Details) - Service Provider Concentration Risk - Revenue	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
10 Largest Service Providers
Concentration Risk [Line Items]
Concentration risk percentage (percent)	57.00%	60.00%	60.00%
Minimum \| Service Provider A
Concentration Risk [Line Items]
Concentration risk percentage (percent)	15.00%	15.00%
Minimum \| Service Provider B
Concentration Risk [Line Items]
Concentration risk percentage (percent)		10.00%	10.00%
Maximum \| Service Provider A
Concentration Risk [Line Items]
Concentration risk percentage (percent)	20.00%	20.00%
Maximum \| Service Provider B
Concentration Risk [Line Items]
Concentration risk percentage (percent)		15.00%	15.00%