Significant Accounting Policies - Amortization (Details)	12 Months Ended
Dec. 31, 2018
Capitalized software \| Maximum
Intangible assets
Amortization period	3 years
Other intangible assets \| Minimum
Intangible assets
Amortization period	1 year
Other intangible assets \| Maximum
Intangible assets
Amortization period	7 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration