Fair Value of Investments on Deposit with Governmental Authorities Narrative (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Investments [Abstract]
Fair value of investments on deposit with governmental authorities	$ 20.5	$ 19.1

Investments on Deposit with Government Authorities, Fair Value Disclosure

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant