Stock Option Plans - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended		12 Months Ended
	Jul. 19, 2021	Aug. 31, 2021	May 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Aug. 07, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant				3,377,416			3,000,000
Stock option expense				$ 3.4	$ 4.9	$ 4.5
Aggregate intrinsic value for outstanding options				20.4
Aggregate intrinsic value for exercisable options				12.8
Total intrinsic value of options exercised				15.7	26.4	2.2
Restricted stock or unit expense				$ 10.9	$ 10.4	$ 15.3
Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant							1,500,000
Performance Vesting Stock Options [Member] | Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			4,293
Percentage of average return on invested capital				20.00%
Reduced percentage of shares earned in stock options plan				66.70%
Shares earned				4,293
Stock based compensation plan, description				The performance criterion for the Fiscal 2022 Employee Performance Stock Option Grant was based upon the achievement of certain levels of return on equity (as defined in the option agreements), ranging from 10.0% to 20.0%, for the fiscal year ending March 31, 2022. All stock options would be earned if the return on equity was 20.0% or greater, and the percentage of shares earned are reduced proportionately to approximately 66.7% if the return on equity was 10.0%. If the Company does not achieve a return on equity of at least 10.0%, all stock options granted would be forfeited.
Share-based compensation vesting period			4 years
Share-based compensation award expiration term			10 years
Performance Vesting Stock Options [Member] | Long Term Compensation Plan [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital			10.00%
Share-based compensation expiration date				Mar. 31, 2023
Performance Vesting Stock Options [Member] | Long Term Compensation Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital			20.00%
Share-based compensation expiration date				Mar. 31, 2025
Time Vesting Stock Options [Member] | Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			3,578
Share-based compensation vesting period			4 years
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period of recognition of unrecognized compensation cost				1 year 9 months 18 days
Unrecognized compensation cost				$ 3.7
Performance Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			52,577
Percentage of average return on invested capital				20.00%
Shares earned				52,577
Stock based compensation plan, description				The performance criterion for the Fiscal 2022 Employee Restricted Stock Performance Award is based upon the achievement of certain levels of return on equity (as defined in the agreement), ranging from 10.0% to 20.0%, for the fiscal year ended March 31, 2022. All restricted shares would be earned if the return on equity was 20.0% or greater, and the percentage of shares earned would be reduced proportionately to approximately 66.7% if the return on equity was 10.0%. If the Company did not achieve a return on equity of at least 10.0%, all awards would be forfeited.
Share-based compensation vesting period			4 years
Reduced percentage of restricted shares				66.70%
Share-based compensation vesting date			Mar. 31, 2025
Performance Vesting Restricted Stock [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital			10.00%
Share-based compensation vesting date			Mar. 31, 2023
Performance Vesting Restricted Stock [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital				20.00%
Time Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			43,816
Share-based compensation vesting period	4 years		4 years
Time Vesting Restricted Stock [Member] | Board of Director [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation vesting period			6 months
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant				259,000
Share-based compensation vesting period		6 months
Weighted-average period of recognition of unrecognized compensation cost				2 years 4 months 24 days
Unrecognized compensation cost				$ 17.2
Restricted Stock [Member] | Board of Director [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		15,720
Restricted Stock And Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant				1,008,690