Taxes (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Line Items]
Effective income tax rate	36.00%	36.50%	36.40%	36.70%
MGE [Member]
Income Tax Disclosure [Line Items]
Effective income tax rate	35.50%	36.50%	35.90%	36.70%