Shares used to calculate earnings per share Shares used to calculate earnings per share (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Notes to Financial Statements [Abstract]
Basic (shares)	49.3	49.0	49.2	49.0
Effect of dilutive stock options and awards (shares)	0.0	0.4	0.0	0.0
Diluted (shares)	49.3	49.4	49.2	49.0
Antidilutive stock options and awards excluded from denominator (shares)	1.5	1.0	1.5	2.1
Share-based goods and nonemployee services transaction, quantity of securities issued (shares)	0.6	0.6	0.5	0.5