Capital (Details 4) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Basic Earnings:
Net income attributable to SLGOP common unitholders	$ 19,464	$ 26,144
Diluted Earnings:
Income attributable to SLGOP common unitholders	$ 19,464	$ 26,144
Basic Earnings:
Units attributable to common unitholders (in shares)	94,086	89,793
Effect of Dilutive Securities:
Stock-based compensation plans (in shares)	216	380
Diluted Units (in shares)	94,302	90,173
Common units excluded from the diluted shares outstanding	988,887	785,929
3.0% exchangeable senior debentures due 2017
Effect of Dilutive Securities:
Interest rate (as a percent)	3.00%
3.0% exchangeable senior debentures due 2027
Effect of Dilutive Securities:
Interest rate (as a percent)	3.00%
4.0% exchangeable senior debentures due 2025
Effect of Dilutive Securities:
Interest rate (as a percent)	4.00%

Aggregate amount of net income allocated to common unitholders.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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