Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Federal tax expense at statutory rate	34.00%	35.00%	34.00%
State income tax expense (net of federal income tax benefit)	4.00%	4.00%	6.00%
Permanent differences associated with tax grants	0.00%	0.00%	5.00%
Permanent differences associated with stock options	(5.00%)	2.00%	4.00%
Other permanent differences	3.00%	2.00%	4.00%
Other	0.00%	(1.00%)	1.00%
Net income tax expense	36.00%	42.00%	54.00%

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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-Publisher SEC

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-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

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-Section 50

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to nondeductible expenses under enacted tax laws, or differences in the methodologies used to determine expense amounts for financial statements prepared in accordance with generally accepted accounting principles, not otherwise listed in the existing taxonomy.

+ References

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to differences in the deductibility or nondeductibility of incentive stock options and other equity-based compensation costs in accordance with generally accepted accounting principles and enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the state and local income tax expense or benefit, net of the federal tax benefit (expense) thereon, recorded during the period.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by research tax credits generated or utilized under enacted tax laws during the period.

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