Stock-based Compensation Plans and Awards - Stock Options Activity (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2017 shares
Stock option activity
Outstanding beginning balance (in shares)	2,856
Options granted (in shares)	37
Options exercised (in shares)	(261)
Options forfeited or canceled (in shares)	(231)
Outstanding ending balance (in shares)	2,401