Fair Value Disclosures (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Excluded Securities from unobservable quantitative information	$ 68.1
Knight Capital [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Percentage of outstanding common stock owned	23.00%

Excluded Securities from Unobservable Quantitative Information

No definition available.

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Namespace Prefix:	luk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration