Benefit Plans Benefit Plans - Defined Contribution Plans (Details) - Employee Contributions First Six Percent [Member]	12 Months Ended
	Dec. 31, 2018
Defined Contribution Plan [Line Items]
Participant Contribution Percentage	6.00%
Effective January 1, 2012 to December 31, 2013 [Member] | Subsequent to July 1, 2003 Hire Date [Member]
Defined Contribution Plan [Line Items]
Retirement savings plan basic match	60.00%
Effective January 1, 2014 to December 31, 2015 [Member] | Prior to July 1, 2003 Hire Date [Member]
Defined Contribution Plan [Line Items]
Retirement savings plan basic match	60.00%
Effective January 1, 2014 to December 31, 2015 [Member] | Subsequent to July 1, 2003 Hire Date [Member]
Defined Contribution Plan [Line Items]
Retirement savings plan basic match	60.00%