Income Taxes (Summary of Income Before Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Abstract]
United States Operations									$ 69,822	$ 170,517	$ 127,682
Foreign Operations									4,017	16,921	11,933
INCOME BEFORE INCOME TAXES	$ 11,687	$ 33,955	$ 19,992	$ 8,205	$ 53,917	$ 58,616	$ 47,612	$ 27,293	$ 73,839	$ 187,438	$ 139,615