Stock Incentive Plans (Details 3) - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Non-vested stock incentive awards
Beginning Balance, Non-vested, shares | shares	987,000
Beginning of Period, Non-vested , Weighted Average Grant Date Fair Value | $ / shares	$ 58.98
Vested, shares | shares	(477,000)
Vested, Weighted Average Grant Date Fair Value | $ / shares	$ 63.15
Granted, shares | shares	247,000
Granted, Weighted Average Grant Date Fair Value | $ / shares	$ 69.78
Terminated, shares | shares	(59,000)
Terminated, Weighted Average Grant Date Fair Value | $ / shares	$ 63.2
Ending Balance, Non-vested, shares | shares	698,000
Ending of Period, Non-vested, Weighted Average Grant Date Fair Value | $ / shares	$ 61