Commitments and Contingencies - Legal Proceedings (Details) (Office of the Massachusetts Attorney General [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Office of the Massachusetts Attorney General [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount	$ 1.5

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

No definition available.

Name:	us-gaap_LitigationSettlementExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration