Antidilutive Shares (Details) - shares shares in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Preferred Stock Outstanding
Antidilutive Securities
Securities Excluded from Computation of Earnings Per Share, Amount	[1]	0.0	0.0	13.7
Stock options
Antidilutive Securities
Stock options 2	[2]	0.0	0.0	0.1

[1] 1We converted all of our 5 1/4% Series B Cumulative Convertible Perpetual Preferred Stock into common stock in October 2013. For purposes of calculating diluted earnings per share for 2013, the potentially dilutive shares would have been pro-rated based on the period they were outstanding but were antidilutive.

[2] These options were outstanding at the end of the respective periods. In any period in which the exercise price is less than the average market price, these options have the potential to be dilutive, and application of the treasury stock method would reduce this amount.