Stock-Based Compensation and Other Incentive Plans (Restricted Stock Unit Activity) (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Time Based Awards
Restricted Stock Common Shares
Outstanding at beginning of period (in shares) | shares	159
Granted (in shares) | shares	92
Forfeited (in shares) | shares	(2)
Canceled (in shares) | shares	(9)
Outstanding at end of period (in shares) | shares	240
Weighted Average Grant Date Fair Value
Outstanding weighted average grant date fair value at beginning of period (in dollars per share) | $ / shares	$ 78.60
Granted (in dollars per share) | $ / shares	$ 81.91
Forfeited (in dollars per share) | $ / shares	78.60
Canceled (in dollars per share) | $ / shares	$ 78.60
Outstanding weighted average grant date fair value at end of period (in dollars per share) | $ / shares	$ 79.87
Performance Based Awards
Restricted Stock Common Shares
Outstanding at beginning of period (in shares) | shares	225
Granted (in shares) | shares	86
Forfeited (in shares) | shares	0
Canceled (in shares) | shares	0
Outstanding at end of period (in shares) | shares	311
Weighted Average Grant Date Fair Value
Outstanding weighted average grant date fair value at beginning of period (in dollars per share) | $ / shares	$ 67.34
Granted (in dollars per share) | $ / shares	$ 101.38
Forfeited (in dollars per share) | $ / shares	0.00
Canceled (in dollars per share) | $ / shares	$ 0.00
Outstanding weighted average grant date fair value at end of period (in dollars per share) | $ / shares	$ 76.75