Basis of Presentation and Summary of Significant Accounting Policies (Details)	Dec. 31, 2012 item
Basis of Presentation and Summary of Significant Accounting Policies
Number of states in which service is provided	14

The number of states the entity operates in as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant