Summary of Significant Accounting Policies Awards Outstanding (Details) - shares	Sep. 30, 2015	Dec. 31, 2014
Stock options
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	855,214	961,377
Restricted Stock Units (RSUs) [Member]
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	2,021,655	1,830,291
Performance Shares [Member]
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	32,000	34,000
Stock appreciation rights
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	531,692	673,068
Market share units
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	563,300	444,272