Earnings Per Share

3 Months Ended

Mar. 31, 2012

Earnings Per Share [Abstract]

Earnings Per Share

Note 4 - Earnings Per Share

Basic earnings per share (EPS) is computed by dividing net income attributable to Questar by the weighted-average number of common shares outstanding during the reporting period. Diluted EPS includes the potential increase in the number of outstanding shares that could result from the exercise of in-the-money stock options, the vesting of restricted stock units and performance shares that are part of the Company's Long-Term Stock Incentive Plan (LTSIP), less shares repurchased under the treasury stock method. Restricted stock units are participating securities for the computation of earnings per share. The application of the two-class method had an insignificant impact on the calculation of both basic and diluted EPS. A reconciliation of the components of basic and diluted shares used in the EPS calculation follows:

	3 Months Ended		12 Months Ended
	March 31,		March 31,
	2012	2011	2012	2011
	(in millions)
Weighted-average basic common shares outstanding	178.2	177.0	177.8	176.2
Potential number of shares issuable under the Company's LTSIP	1.1	1.5	1.3	2.3
Weighted-average diluted common shares outstanding	179.3	178.5	179.1	178.5