Retirement Benefits Plans (Details Textual) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Deferred Compensation, Benefits Owed by Participants	$ 25
Maximum
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation arrangement with individual service period (in years)	10 years

Deferred compensation arrangement with individual service period.

No definition available.

Name:	sxc_DeferredCompensationArrangementWithIndividualServicePeriod
Namespace Prefix:	sxc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration