Computation of Basic and Diluted Earnings per Common Share - Summary of Computation of Basic and Diluted Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings per common share
Net income attributable to SCUSA	$ 246,481	$ 181,918	$ 327,947	$ 472,320
Weighted average number of common shares outstanding before restricted participating shares	348,243,007	346,171,491	347,881,776	346,168,144
Weighted average number of participating restricted common shares outstanding	583,890	0	583,890	0
Weighted average number of common shares outstanding	348,826,897	346,171,491	348,465,666	346,168,144
Earnings per common share (in usd per share)	$ 0.71	$ 0.53	$ 0.94	$ 1.36
Earnings per common share - assuming dilution
Net income attributable to SCUSA	$ 246,481	$ 181,918	$ 327,947	$ 472,320
Weighted average number of common shares outstanding	348,826,897	346,171,491	348,465,666	346,168,144
Effect of employee stock-based awards (in shares)	7,555,024	0	7,542,622	0
Weighted average number of common shares outstanding - assuming dilution	356,381,921	346,171,491	356,008,288	346,168,144
Earnings per common share - assuming dilution (in usd per share)	$ 0.69	$ 0.53	$ 0.92	$ 1.36