Equity Accumulated Other Comprehensive Income Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2017
Components of accumulated other comprehensive income
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ (8,794)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	8,544	$ 13,175
Unrealized gains (losses) on equity securities	0	(3,222)	$ 4,614
Unrealized gains (losses) on cash flow hedges	1,059	(1,059)	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	488	(313)	1,535
Other Comprehensive Income (Loss), Unrealized Gains (Losses)		(4,475)
Other Comprehensive Income Loss Reclassification Adjustment From AOCI Foreclosed Asset	(956)	(156)
Other comprehensive income	103	(4,631)
Ending balance	(147)	8,544	13,175
Unrealized Gains (Losses) Equity Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	8,794	12,016
Unrealized gains (losses) on equity securities	0	(3,222)
Other comprehensive income	0	(3,222)
Ending balance	0	8,794	12,016
Unrealized Gains Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	3,039	3,531
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), Adjustments, after Tax	(468)	(492)
Other comprehensive income	(468)	(492)
Ending balance	2,571	3,039	3,531
Unrealized Gains (Losses) Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(1,059)	171
Unrealized gains (losses) on cash flow hedges	1,059	(1,059)
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), Reclassification, before Tax	0	(171)
Other comprehensive income	1,059	(1,230)
Ending balance	0	(1,059)	171
Unrealized Losses Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(2,230)	(2,543)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax		(194)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	(488)	507
Other comprehensive income	(488)	313
Ending balance	(2,718)	$ (2,230)	$ (2,543)
Unallocated Net Income (Loss)
Components of accumulated other comprehensive income
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ (8,794)