Employee Stock and Savings Plans - Summary of Restricted Stock Unit and Performance Stock Unit Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Restricted stock units
Shares
Restricted stock units - Balance at beginning of period (in shares) | shares	1,942
Granted (in shares) | shares	569
Forfeited (in shares) | shares	(173)
Vested (in shares) | shares	(517)
Restricted stock units - Balance at end of period (in shares) | shares	1,821
Weighted- Average Grant Date Fair Value
Restricted stock units - Balance at beginning of period (in dollars per share) | $ / shares	$ 44.35
Granted (in dollars per share) | $ / shares	71.13
Forfeited (in dollars per share) | $ / shares	54.72
Vested (in dollars per share) | $ / shares	39.03
Restricted stock units - Balance at end of period (in dollars per share) | $ / shares	$ 53.22
Performance Shares
Shares
Restricted stock units - Balance at beginning of period (in shares) | shares	402
Granted (in shares) | shares	164
Forfeited (in shares) | shares	(42)
Vested (in shares) | shares	0
Restricted stock units - Balance at end of period (in shares) | shares	524
Weighted- Average Grant Date Fair Value
Restricted stock units - Balance at beginning of period (in dollars per share) | $ / shares	$ 52.16
Granted (in dollars per share) | $ / shares	75.40
Forfeited (in dollars per share) | $ / shares	55.42
Vested (in dollars per share) | $ / shares	0.00
Restricted stock units - Balance at end of period (in dollars per share) | $ / shares	$ 57.60