Employee Benefit Plans (Defined Benefit Pension Plan) (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) pension_plan	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of qualified defined pension plans | pension_plan	1
Pension contributions	$ 0	$ 0
Amount included in accumulated other comprehensive income not yet recognized as components of net periodic benefit cost	$ 24,500,000	$ 33,300,000
Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefits payable calculation, highest earnings service period	5 years
Benefits payable calculation, service period	10 years
Age limit for early retirement of participants under cash balance plan	55 years
Completion period of credited service for participants under cash balance plan	10 years
Years of consecutive service to be eligible to retire with full benefits	35 years
Minimum employee retirement age to receive full benefits	62 years
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Term of obligation based on expected retirement dates	7 years
Average long-term rate of return, company goal	5.20%