Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2017

Accounting Policies [Abstract]

Awards outstanding [Table Text Block]

The following table presents the number of shares or units outstanding for each award type as of March 31, 2017 and December 31, 2016, respectively, (in thousands):

Award type	March 31, 2017	December 31, 2016
Stock options	478	734
Restricted stock units (time-based)	2,347	2,237
Restricted stock units (market-based)	460	460
Stock appreciation rights	490	515
Market stock units	347	342

Market Stock Units Valuation Assumptions [Table Text Block]

The weighted average assumptions used to value the MSUs granted during the three months ended March 31, 2017 were as follows:

	March 31, 2017
Volatility	45.88%
Risk-free interest rate	1.52%
Expected option life in years	3.10
Dividend yield	—