Equity-Based Compensation Equity-Based Compensation (Summary of Outstanding Stock Options By Exercise Price Range) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)		55,886
Weighted Avg. Remaining Contractual Life (in years)	1 year 6 months 7 days
19.2569
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Upper Limit (in dollars per share)	19.2569
Options outstanding (in shares)		8,028
Weighted Avg. Remaining Contractual Life (in years)	8 months 1 day
30.9204
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Upper Limit (in dollars per share)	30.9204
Options outstanding (in shares)		47,858
Weighted Avg. Remaining Contractual Life (in years)	1 year 8 months 1 day