Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2018
U.S. Department of Justice Matter
Loss Contingencies [Line Items]
Legal expenses	$ 1.6	$ 3.3

The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

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