Share-Based Payments Non-vested (Details) - $ / shares shares in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Rsus and Dsus [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards outstanding at the beginning of the period (in shares)	0.7
Granted (in shares)	0.2
Vested (in shares)	(0.2)
Forfeited (in shares)	(0.1)
Non-vested awards outstanding at the end of the period (in shares)	0.6
Granted, weighted-average grant date fair value (in dollars per unit)	$ 70.83
Forfeited, weighted-average grant date fair value (in dollars per unit)	50.17
Non-vested, weighted-average grant date fair value at the beginning of the period (in dollars per unit)	47.75
Vested, weighted-average grant date fair value (in dollars per unit)	42.85
Non-vested, weighted-average grant date fair value at the end of the period (in dollars per unit)	$ 55.59
PUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards outstanding at the beginning of the period (in shares)	0.5
Granted (in shares)	0.0
Vested (in shares)	(0.5)
Forfeited (in shares)	0.0
Non-vested awards outstanding at the end of the period (in shares)	0.0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Intrinsic Value, Amount Per Share	$ 0.00		$ 3.22
Granted, weighted-average grant date fair value (in dollars per unit)	0.00
Forfeited, weighted-average grant date fair value (in dollars per unit)	0.00
Vested, weighted-average grant date fair value (in dollars per unit)	$ 2.89
PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards outstanding at the beginning of the period (in shares)	0.4
Granted (in shares)	0.1
Vested (in shares)	0.0
Forfeited (in shares)	0.0
Non-vested awards outstanding at the end of the period (in shares)	0.5
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Intrinsic Value, Amount Per Share	$ 65.73
Granted, weighted-average grant date fair value (in dollars per unit)	74.42	$ 58.69
Forfeited, weighted-average grant date fair value (in dollars per unit)	0.00
Non-vested, weighted-average grant date fair value at the beginning of the period (in dollars per unit)	50.49
Vested, weighted-average grant date fair value (in dollars per unit)	0.00
Non-vested, weighted-average grant date fair value at the end of the period (in dollars per unit)	$ 57.05