Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Basis of Presentation
Amount of the prior year first quarter impact had reclassification been made from selling, general and administrative costs to cost of sales	$ 5.8

Represents the amount of the prior year first quarter impact if reclassification had been made from selling, general and administrative costs to cost of sales.

No definition available.

Name:	wlt_AmountOfPriorYearImpactOfReclassificationFromSellingGeneralAndAdministrativeExpenseToCostOfSale
Namespace Prefix:	wlt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration