Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Income Taxes [Abstract]
Income tax expense	$ 18,719,000	$ 14,305,000	$ 24,076,000	$ 20,519,000
Income before taxes	41,996,000	49,661,000	56,477,000	84,836,000
Effective income tax rate	44.60%	28.80%	42.60%	24.20%
Unrecognized tax benefits	$ 23,000,000		$ 23,000,000		$ 31,600,000