Summary of Significant Accounting Policies Awards Outstanding (Details)	Jun. 30, 2013	Dec. 31, 2012
Stock options
Awards outstanding [Line Items]
Awards outstanding, Number	1,214,690	1,474,828
Restricted stock units
Awards outstanding [Line Items]
Awards outstanding, Number	1,596,935	1,182,726
Stock appreciation rights
Awards outstanding [Line Items]
Awards outstanding, Number	736,717	789,637
Market share units
Awards outstanding [Line Items]
Awards outstanding, Number	469,000	205,000