XML 17 R33.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Significant Accounting Policies Revenue and Expense Recognition (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
Significant Accounting Policies [Abstract] |  |  |
Fuel surcharge revenue | $ 107.8 | $ 75.3 | $ 53.3

X
- Definition Fuel surcharge revenue + References No definition available. + Details
Name: | htld_FuelSurchargeRevenue
Namespace Prefix: | htld_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | htld_SignificantAccountingPoliciesAbstract
Namespace Prefix: | htld_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration