Annual report pursuant to Section 13 and 15(d)

Income Taxes Income Taxes (Effective Income Tax Rate Reconciliation) (Details)

v3.8.0.1
Income Taxes Income Taxes (Effective Income Tax Rate Reconciliation) (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation, Percent [Abstract]      
Provision at statutory rate 35.00% 35.00% 35.00%
State income taxes, net of federal benefit 1.00% 1.30% 1.40%
Foreign taxes 0.00% (0.30%) 0.20%
Foreign earnings repatriation 3.90% 0.20% 0.20%
Valuation allowance 1.00% 1.00% 0.90%
Permanent differences (2.10%) (0.60%) (0.20%)
Impact of Tax Cuts and Jobs Act (25.40%)    
Impact of foreign currency tax regulation 0.40% 1.00% 0.00%
Other, net (0.30%) (0.10%) (0.50%)
Total income tax expense 13.50% 37.50% 37.00%