Stock-Based Compensation, Summary of Stock Option Activity (Details) - Stock Options and Stock Appreciation Rights [Member] shares in Thousands	9 Months Ended
	Sep. 30, 2018 $ / shares shares
Shares [Roll Forward]
Outstanding, beginning balance (in shares) | shares	12,834
Granted (in shares) | shares	848
Exercised or settled (in shares) | shares	(752)
Forfeited (in shares) | shares	(433)
Outstanding, ending balance (in shares) | shares	12,497
Vested (in shares) | shares	8,612
Outstanding Weighted-Average Exercise Price [Abstract]
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 9.54
Granted (in dollars per share) | $ / shares	31.74
Exercised or settled (in dollars per share) | $ / shares	8.36
Forfeited (in dollars per share) | $ / shares	16.21
Outstanding, ending balance (in dollars per share) | $ / shares	10.88
Vested (in dollars per share) | $ / shares	$ 9.03