New Accounting Pronouncements - Impact of Recently Adopted Accounting Standards (Details)	6 Months Ended
Jun. 30, 2018
Revenue recognition
Perpetual software licenses, estimated useful life	5 years
Customer relationship, commission costs amortization period	5 years

Customer Relationship, Capitalized Contract Cost, Amortization Period

No definition available.

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration