Holly-Frontier Merger (Narrative) (Details) (USD $) In Billions, except Share data in Millions, unless otherwise specified	1 Months Ended
	Jul. 31, 2011	Jul. 02, 2011
Business Acquisition [Line Items]
Shares converted at acquisition	102.8
Common stock to be issued per share of Frontier stock	0.4811
Aggregate consideration paid in connection with merger	$ 3.7
Market closing price, per share		$ 35.93