Stock Incentive Plans (Non-Vested Restricted Stock Incentive Awards) (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Non-vested stock incentive awards
Beginning Balance, Non-vested, shares | shares	698,000
Vested, shares | shares	(166,000)
Granted, shares | shares	723,000
Terminated, shares | shares	(35,000)
Ending Balance, Non-vested, shares | shares	1,220,000
Beginning of Period, Non-vested , Weighted Average Grant Date Fair Value (in USD per share) | $ / shares	$ 61.00
Vested, Weighted Average Grant Date Fair Value (in USD per share) | $ / shares	63.88
Granted, Weighted Average Grant Date Fair Value (in USD per share) | $ / shares	54.16
Terminated, Weighted Average Grant Date Fair Value (in USD per share) | $ / shares	60.90
Ending of Period, Non-vested, Weighted Average Grant Date Fair Value (in USD per share) | $ / shares	$ 62.56