Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Segments (Details)	12 Months Ended
Segments (Details)	Dec. 31, 2016 segment	Dec. 31, 2016 Segment	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of reportable segments	3	3
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Percentage of assets			68.00%	71.00%	72.00%