Investments (Details) - Certificates of Deposit	9 Months Ended
Sep. 30, 2015
Minimum
Schedule of Held-to-maturity Securities
Investment Term	3 months
Maximum
Schedule of Held-to-maturity Securities
Investment Term	18 months

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