Employee Benefit Plans - Target Plan Asset Allocation (Details)	Jun. 30, 2018
Defined Benefit Plan Disclosure
Target Plan Asset Allocations	100.00%
U.S. large cap equity securities
Defined Benefit Plan Disclosure
Target Plan Asset Allocations	37.00%
U.S. small cap equity securities
Defined Benefit Plan Disclosure
Target Plan Asset Allocations	4.60%
International equity securities
Defined Benefit Plan Disclosure
Target Plan Asset Allocations	22.40%
Debt securities
Defined Benefit Plan Disclosure
Target Plan Asset Allocations	30.00%
Real estate
Defined Benefit Plan Disclosure
Target Plan Asset Allocations	6.00%