Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Income Tax Disclosure [Abstract]
Effective tax rate (in hundredths)		19.70%		21.40%
Net discrete items	$ (372)	$ 22,338	$ 1,060	$ 30,354
Pre-discrete tax rate	27.40%	27.20%	27.10%	27.20%