Annual report pursuant to Section 13 and 15(d)

Income Taxes (Reasons For The Difference Between Provision For Income Taxes) (Details)

v3.8.0.1
Income Taxes (Reasons For The Difference Between Provision For Income Taxes) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Taxes [Abstract]      
Income tax expense at statutory rate $ 42,893 $ 40,293 $ 39,416
Effect of state taxes, net of federal tax benefit 2,735 1,796 1,620
Effect of federal rate change, net of federal tax benefit (47,722)    
Effect of state rate changes on net deferred liabilities 118 (1,433) 1,448
Change in valuation allowance 275 (549) (47)
Non-deductible items 460 317 194
Tax credits (1,733) (515) (307)
Other   263 (13)
Income Tax Expense (Benefit), Total $ (2,974) $ 40,172 $ 42,311