Stock Incentive Compensation and Employee Benefit Plans (Schedule of Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted options outstanding:
Beginning balance (in shares)	206,795	408,212	767,830
Options granted (in shares)	0	0	0
Options forfeited (in shares)	0	0	0
Options expired (in shares)	0	0	0
Options exercised (in shares)	(174,794)	(201,417)	(359,618)
Ending balance (in shares)	32,001	206,795	408,212	767,830
Weighted average exercise price:
Weighted average exercise price, beginning balance (in usd per share)	$ 53.17	$ 51.90	$ 48.71
Options granted, Weighted average exercise price (in usd per share)	0.00	0.00	0.00
Options forfeited, Weighted average exercise price (in usd per share)	0.00	0.00	0.00
Options expired, Weighted average exercise price (in usd per share)	0.00	0.00	0.00
Options exercised, Weighted average exercise price (in usd per share)	53.04	50.59	45.09
Weighted average exercise price, ending balance (in usd per share)	$ 53.86	$ 53.17	$ 51.90	$ 48.71
Weighted average remaining contractual life	2 months 12 days	10 months 24 days	1 year 7 months 6 days		2 years
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value	$ 2,295	$ 17,174	$ 25,020	$ 37,246
Options exercised, Aggregate intrinsic value	$ 15,945	$ 14,806	$ 21,205
Range of Exercise Prices [Abstract]
Exercise price range, lower range limit (in usd per share)		$ 50.71	$ 42.66	$ 37.51
Exercise price range, upper range limit (in usd per share)		$ 59.66	$ 59.66	$ 59.66
Total options outstanding (in usd per share)	$ 53.86
Total options exercisable (in usd per share)	$ 53.86
Total options exercisable (in shares)	32,001
Total options exercisable, Weighted average exercise price (in usd per share)	$ 53.86
Total options exercisable, Weighted average remaining contractual life	2 months 12 days
Total options exercisable, Aggregate intrinsic value	$ 2,295