Acquisitions - Narratives (Details)	12 Months Ended
Dec. 31, 2014 branches
Business Acquisition [Line Items]
Acquired entity number of branches	20,000us-gaap_NumberOfStores
Intangible Asset Weighted-average Amortization Period	10 years 10 months 25 days

Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration