Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Income tax expense	$ 25,659	$ 19,974	$ 82,012	$ 49,009
Effective tax rates (percent)	38.50%	33.60%	36.90%	30.30%
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions					$ 6,449