Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Apr. 16, 2013 Subsequent Event [Member]
Loss Contingencies [Line Items]
IRS proposed adjustments to tax years 2000 through 2002, before penalty and interest	$ 16,500
Potential penalty, percentage of tax assessment	20.00%
Maximum Term for Option to Appeal		90 days
IRS proposed settlement, including penalties and interest		13,000
Tax Examination, Estimate of Negative Impact on Cash Flows in Third Quarter		13,000
Tax Examination, Estimate of Potential Income Tax Charge in Second Quarter		$ 20,000