Stock-Based Compensation (Details) 4 (USD $)
6 Months Ended
Jun. 30, 2013
Restricted Stock Units Performance Based
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Vesting period 3 years
LTIP Plan | Restricted Stock Units Time Based
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of restricted units granted 251,970
Number of restricted units outstanding 726,374
LTIP Plan | Restricted Stock Units Performance Based
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of restricted units granted 253,980
Number of restricted units outstanding 682,216
LTIP Plan | Restricted Stock Units (RSUs)
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Weighted average grant date value of resticted units granted (per unit) $ 56.25
Catalyst | Restricted Stock Units Time Based
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of restricted units granted 103,870
Number of restricted units outstanding 218,854
Catalyst | Restricted Stock Units Performance Based
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of restricted units granted 21,340
Number of restricted units outstanding 13,280
Catalyst | Restricted Stock Units (RSUs)
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Weighted average grant date value of resticted units granted (per unit) $ 55.82
Straight Line Vesting Basis | Restricted Stock Units Time Based | Minimum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Vesting period 2 years
Straight Line Vesting Basis | Restricted Stock Units Time Based | Maximum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Vesting period 4 years
Cliff Vesting | Restricted Stock Units Time Based | Minimum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Vesting period 3 years
Cliff Vesting | Restricted Stock Units Time Based | Maximum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Vesting period 4 years