Income Taxes (Schedule of Effective Income Tax Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax at statutory rate	$ 44,611	$ 70,406	$ 56,621
State income taxes, net of federal tax benefits	3,032	6,627	4,641
Non-deductible meals and entertainment	1,549	1,687	1,497
Income tax credits	(1,900)	(1,700)	(1,600)
Other, net	1,039	427	1,965
Total income tax expense	$ 48,331	$ 77,447	$ 63,124