Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
U.S. Federal tax rate	35.00%		35.00%
Income tax provision	$ 17,969	$ 25,714	$ 19,061	$ 39,586
Foreign affiliate investment tax benefit, percent			34.40%
Effective tax rate	35.70%	34.20%		34.40%