Stock-Based Compensation (Performance Share Awards Activity) (Details) - Performance Shares	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Performance Shares (in shares):
Balance at beginning of period (in shares) | shares	1,442,218
Grants (in shares) | shares	517,104
Forfeitures (in shares) | shares	(57,120)
Payouts (in shares) | shares	(509,690)
Balance at end of period (in shares) | shares	1,392,512
Weighted Average Grant Date Fair Value (in dollars per share):
Balance at beginning of period (in dollars per share) | $ / shares	$ 75.85
Grants (in dollars per share) | $ / shares	87.35
Forfeitures (in dollars per share) | $ / shares	81.39
Payouts (in dollars per share) | $ / shares	0.00
Balance at end of period (in dollars per share) | $ / shares	$ 79.97