Share-based Payments, Stock Option Activity (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, shares (in shares)	1,036,359
Options outstanding, weighted average exercise price (in dollars per share)	$ 14.92
Options outstanding, weighted average remaining life	6 years 5 months 23 days
Options outstanding, aggregate intrinsic value	$ 16,384,000
Options exercisable, shares (in shares)	751,746
Options exercisable, weighted average exercise price (in dollars per share)	$ 9.67
Options exercisable, aggregate intrinsic value	$ 15,832,000
$4.17 to $6.25 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price of options, lower range (in dollars per share)	$ 4.17
Exercise price of options, upper range (in dollars per share)	$ 6.25
Options outstanding, shares (in shares)	74,000
Options outstanding, weighted average exercise price (in dollars per share)	$ 5.29
Options outstanding, weighted average remaining life	1 year 10 months 24 days
Options outstanding, aggregate intrinsic value	$ 1,883,000
Options exercisable, shares (in shares)	74,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 5.29
Options exercisable, aggregate intrinsic value	$ 1,883,000
$6.46 to $7.43 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price of options, lower range (in dollars per share)	$ 6.46
Exercise price of options, upper range (in dollars per share)	$ 7.43
Options outstanding, shares (in shares)	359,167
Options outstanding, weighted average exercise price (in dollars per share)	$ 6.48
Options outstanding, weighted average remaining life	5 years 8 months 8 days
Options outstanding, aggregate intrinsic value	$ 8,710,000
Options exercisable, shares (in shares)	359,167
Options exercisable, weighted average exercise price (in dollars per share)	$ 6.48
Options exercisable, aggregate intrinsic value	$ 8,710,000
$9.32 to $19.94 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price of options, lower range (in dollars per share)	$ 9.32
Exercise price of options, upper range (in dollars per share)	$ 19.94
Options outstanding, shares (in shares)	235,450
Options outstanding, weighted average exercise price (in dollars per share)	$ 9.96
Options outstanding, weighted average remaining life	5 years 9 months 29 days
Options outstanding, aggregate intrinsic value	$ 4,891,000
Options exercisable, shares (in shares)	235,450
Options exercisable, weighted average exercise price (in dollars per share)	$ 9.96
Options exercisable, aggregate intrinsic value	$ 4,891,000
$22.93 to $34.17 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price of options, lower range (in dollars per share)	$ 22.93
Exercise price of options, upper range (in dollars per share)	$ 34.17
Options outstanding, shares (in shares)	367,742
Options outstanding, weighted average exercise price (in dollars per share)	$ 28.28
Options outstanding, weighted average remaining life	8 years 7 months 6 days
Options outstanding, aggregate intrinsic value	$ 900,000
Options exercisable, shares (in shares)	83,129
Options exercisable, weighted average exercise price (in dollars per share)	$ 26.55
Options exercisable, aggregate intrinsic value	$ 348,000
Stock Options [Member]
Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)	984,066
Granted (in shares)	186,924
Exercised (in shares)	(133,731)
Forfeited (in shares)	(900)
Outstanding at end of period (in shares)	1,036,359	984,066
Weighted Average Exercise Price [Roll Forward]
Outstanding at beginning of period (in dollars per share)	$ 11.98
Granted (in dollars per share)	28.70
Exercised (in dollars per share)	12.43
Forfeited (in dollars per share)	29.50
Outstanding at end of period (in dollars per share)	$ 14.92	$ 11.98
Number of stock options unvested (in shares)	284,613
Weighted average exercise price of stock options unvested (in dollars per share)	$ 13.04
Pre-tax intrinsic value of options exercised	$ 2,477,000	$ 14,002,000	$ 1,955,000
Fair value of vested stock options	$ 1,290,000	$ 905,000	$ 978,000
Closing stock price (in dollars per share)	$ 30.73
Total unrecognized compensation expense, options	$ 2,666,000
Weighted average vesting period over which compensation expense is expected to be recognized	1 year 10 months 24 days