Summary of Significant Accounting Policies - Fair Value (Details) (Fair Value, Measurements, Recurring [Member], Fair Value, Inputs, Level 1 [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability for deferred compensation	$ 1.3

Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant