Benefit Plans - Additional Information (Detail) - USD ($)		12 Months Ended
	Dec. 01, 2016	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Unearned Employee Stock Ownership Plan shares		6,022,000	6,022,000
ESOP Shares Released on a Monthly Basis		16,725
ESOP Compensation Expense		$ 2,464,000	$ 2,641,000	$ 2,784,000
ESOP Liability		$ 19,500	$ 18,000
Share-based Payment Award, Number of Shares Available for Grant		300,000
Percentage of net income for dividend payout ratio		50.00%
Vested options exercised		48,314	9,565	62,216
Vested options, aggregate intrinsic value		$ 235,000	$ 38,000	$ 470,000
Share-based payment award, number of shares issued		48,314	9,565
Cash proceeds from stock option		$ 423,000	$ 102,000	482,000
Income tax benefit		$ 69,000	13,000	192,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares		2,025,423
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$ 4,800,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		4 years 6 months
Employee Stock Option [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Compensation Expense		$ 2,000,000	2,000,000	1,300,000
Tax Benefit (Expense) from Compensation Expense		$ 453,000	$ 520,000	$ 235,000
Restricted Stock [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		233,000	0	1,387,390
Share-based Compensation Expense		$ 4,100,000	$ 4,300,000	$ 2,600,000
Tax Benefit from Compensation Expense		1,500,000	1,500,000	1,100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$ 11,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		4 years 6 months
Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value		$ 4,128,492	$ 4,354,754	208,000
Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		935,244
Restricted Stock [Member] | Vesting Contingent on Performance and Service Conditions [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		99,000
Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		325,000	356,000
Stock Compensation Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Compensation Expense		$ 6,100,000	$ 6,300,000	$ 3,900,000
Multiemployer Plans, Postretirement Benefit [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Multiemployer Plan Number		001
Defined Benefit Plan, Funded Percentage			107.73%	104.23%
Multiemployer Plans, Plan Contributions			$ 164,600,000	$ 367,100,000
Multiemployer Plans, Plan Expenses		$ 967,000	1,115,000	1,235,000
Multiemployer Plans, Postretirement Benefit [Member] | Maximum [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Percent of Total Plan Contributions		5.00%
Employees’ Savings and Profit Sharing Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum Annual Contribution Per Employee		75.00%
Employer Matching Contribution		3.50%
Defined Contribution Plan, eligible employee contribution		6.00%
Defined Contribution Plan, Cost Recognized		$ 1,047,000	872,000	762,000
Benefit Equalization Plan ("BEP") [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
ESOP Compensation Expense		47,000	24,000	34,000
Defined Benefit Plan, Accumulated Other Comprehensive Income Net (Losses) Gains, after Tax		(987,000)	(868,000)
Defined benefit plan, future amortization of gain (loss)		(56,000)
Defined Benefit Plan, Benefits Paid		235,000	233,000	231,000
Defined Benefit Plan, Contributions by Employer		235,000	233,000	231,000
Defined benefit plan, expected future benefit payments, next twelve months		234,000
Atlas Bank Retirement Income Plan ("ABRIP") [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan Expected Future Contribution Next Twelve Months		0
Defined Benefit Plan, Accumulated Other Comprehensive Income Net (Losses) Gains, after Tax		(837,000)	(836,000)
Defined benefit plan, future amortization of gain (loss)		(4,240)
Defined Benefit Plan, Benefits Paid		213,000	204,000
Defined benefit plan, expected future benefit payments, next twelve months		142,000
Postretirement Welfare Plan [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive Income Net (Losses) Gains, after Tax		468,000	536,000
Defined benefit plan, future amortization of gain (loss)		41,000
Defined Benefit Plan, Benefits Paid		6,000	7,000	7,000
Defined Benefit Plan, Contributions by Employer		6,000	7,000	7,000
Defined benefit plan, expected future benefit payments, next twelve months		30,000
Directors' Consultation and Retirement Plan ("DCRP") [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive Income Net (Losses) Gains, after Tax		273,000	355,000
Defined benefit plan, future amortization of gain (loss)		0
Defined Benefit Plan, Benefits Paid		60,000	60,000	60,000
Defined Benefit Plan, Contributions by Employer		60,000	$ 60,000	$ 60,000
Defined benefit plan, expected future benefit payments, next twelve months		$ 84,000
2016 Equity Incentive Plan [Member] | Employee Stock Option [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Number of Shares Authorized		3,687,628
Share-based Payment Award, Number of Shares Available for Grant		418,628
Share-based Payment Award, Award Vesting Period		5 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
2016 Equity Incentive Plan [Member] | Restricted Stock [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Number of Shares Authorized		1,523,696
Share-based Payment Award, Number of Shares Available for Grant	1,387,390
Share-based Payment Award, Number of Shares Available for Grant		45,306
Share-based Payment Award, Award Vesting Period		5 years
2016 Equity Incentive Plan [Member] | Restricted Stock [Member] | Vesting Contingent on Performance and Service Conditions [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Award Vesting Period		5 years	5 years
Shares vesting service period conditioned upon performance targets		1 year
Shares vesting service period over each of latter four years expected to be determined annually		2 years
2016 Equity Incentive Plan [Member] | Directors And Certain Officers [Member] | Employee Stock Option [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Number of Shares Available for Grant	3,290,000
2016 Equity Incentive Plan [Member] | Directors And Certain Officers [Member] | Performance Based Stock Awards [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Number of Shares Available for Grant	488,000
2016 Equity Incentive Plan [Member] | Directors And Certain Officers [Member] | Service Based Stock Awards [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based Payment Award, Number of Shares Available for Grant	899,390
First Step Conversion and Stock Offering [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer Loan to ESOP		$ 17,457,000
Unearned Employee Stock Ownership Plan shares		2,409,764
ESOP Loan - Maturity Date		Mar. 31, 2017
ESOP Loan - Interest Rate		5.50%
Second Step Conversion and Stock Offering [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer Loan to ESOP		$ 36,125,000
Unearned Employee Stock Ownership Plan shares		3,612,500
ESOP Loan - Interest Rate		3.25%
Employer Additional Loan to ESOP		$ 3,788,000
ESOP Loan - Principal Balance		$ 39,913,000
ESOP Loan - Maturity Period		20 years