Employee Benefit Plans - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	$ 29,700	$ 27,600
Unrecognized net actuarial loss	$ 6,700	$ 800
Expected return on plan assets	4.90%	4.90%
Expected contributions next twelve months	$ 3,100
Expected contributions in year two	3,700
Expected contributions in year three	3,900
Expected contributions in year four	4,000
Expected contributions in year five	4,200
Expected contributions in year six	4,300
Expected contributions thereafter	23,500
Fair value of plan assets	62,267	$ 58,781	$ 59,396
Projected benefit obligation	91,935	86,341	87,387
Net periodic benefit expense (income)	242	(14)
Employer contributions	4,034	0
Supplemental Executive Retirement Plan (SERP)
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 8,600	8,200	6,900
United States Plan
Defined Benefit Plan Disclosure [Line Items]
Required years of service for plan eligibility	1 year
Employer contributions	$ 67,600	56,700	47,500
Deferred Profit Sharing Plan (DPSP)
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	2,500	2,800	$ 1,800
Pension Plan of Immaterial Acquisitions
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,300	7,500
Projected benefit obligation	7,900	7,400
Net periodic benefit expense (income)	$ 600	$ (100)