Amount of short-term borrowings reclassified as long-term based on our ability and intent to refinance.

Name:	unp_DebtReclassifiedAsLongTerm
Namespace Prefix:	unp
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Name:	unp_ShelfRegistrationStatementAndSignificantNewBorrowingsAbstract
Namespace Prefix:	unp
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration