Stock Options And Other Stock Plans (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Share-based Compensation Arrangements [Line Items]
Shares of common stock authorized and available	70,318,887	70,730,692	72,151,415
Union Pacific Corporation 2000 Directors Plan [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Restricted shares outstanding	36,000
Common stock reserved for issuance	2,200,000
Initial grant of retention stock share/units description	Under the Directors Plan, each non-employee director, upon his or her initial election to the Board of Directors, received a grant of 4,000 retention shares or retention stock units.
Union Pacific Corporation 2004 Stock Incentive Plan [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Stock options, shares outstanding	231,807
Common stock reserved for issuance	84,000,000
Union Pacific Corporation 2013 Stock Incentive Plan [Member]
Schedule of Share-based Compensation Arrangements [Line Items]
Stock options, shares outstanding	3,269,780
Retention shares and stock units outstanding	2,671,584
Common stock reserved for issuance	78,000,000