Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		3 Months Ended			9 Months Ended
		Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash payment per share to Airgas stockholders			$ 143		$ 143
Stock-based compensation expense			$ 4,731	$ 4,785	$ 24,303	$ 25,618
Equity Incentive Plan [Member] | Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of stock options granted					$ 19.87	$ 28.72
Shares available for grant			2.3		2.3
Unrecognized compensation expense related to non-vested stock options			$ 38,000		$ 38,000
Weighted-average vesting period of non-vested stock options (in years)					1 year 8 months
Stock-based compensation expense	[1]		$ 3,525	3,718	$ 21,010	$ 22,452
Employee Stock Purchase Plan [Member] | Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of stock options granted					$ 17.59	$ 20.44
Shares available for grant			1.0		1.0
Stock-based compensation expense			$ 1,206	$ 1,067	$ 3,293	$ 3,166
Employee Stock Purchase Plan [Member] | Stock Option [Member] | Scenario, Forecast [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 0

[1] Stock-based compensation expense related to stock options granted under the Company’s Equity Incentive Plan is highest during the Company’s fiscal first quarter ended June 30th relative to other quarters during the year. This is primarily due to a retirement-eligible vesting provision under the plan and the timing of the majority of the Company’s stock option awards each year during its fiscal first quarter.