Employee Benefit Plans (Details 7) employee in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($) agreement unit location	Dec. 31, 2015 unit location employee	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
Defined Contribution Plan
Employee's maximum contribution to 401 (k) defined contribution plan (as a percent)	50.00%
Percentage of employer's matching contribution of first 3% of participant's contribution, option one	100.00%
Maximum percentage of contribution by employee in order to be eligible for 100% matching portion under the plan, option one	3.00%
Percentage of employer's matching contribution of next 2% of participant's contribution, option one	50.00%
Maximum additional percentage of contribution by employee in order to qualify for 50% matching portion under the plan, option one	2.00%
Percentage of employer's matching contribution of first 6% of participant's contribution, option two	50.00%
Maximum percentage contribution by employee in order to be eligible for 50% matching portion under the plan, option two	6.00%
Percentage of employer's matching contribution of first 3% of participant's contribution, option three	100.00%
Maximum percentage of contribution by employee in order to be eligible for 100% matching portion under the plan, option three	3.00%
Percentage of employer's matching contribution of next 3% of participant's contribution, option three	50.00%
Maximum additional percentage of contribution by employee in order to qualify for 50% matching portion under the plan, option three	3.00%
Automatic enrollment vesting period (in years)	1 year
Non-elective contribution vesting period (in years)	3 years
Percentage of participant's pre-tax contribution in automatic enrollment, option four	6.00%
Percentage of employer's matching contribution of first 3% of participant's contribution in automatic enrollment, option four	100.00%
Percentage of participant's contribution in automatic enrollment for which 100% of employer's matching contribution has been made, option three	3.00%
Percentage of employer's matching contribution of next 3% of participant's contribution in automatic enrollment, option four	50.00%
Percentage of participant's contribution in automatic enrollment for which 50% of employer's matching contribution has been made, option three	3.00%
Employer contributions | $	$ 41,028		$ 51,205	$ 48,379
Collective bargaining agreements
Number of employees eligible under the plan | employee		9
Number of locations at which the majority of covered employees work | location	5	5
Percentage of employees covered by collective bargaining agreements	20.00%	20.00%
Number of locations with multiple collective bargaining agreements | location	1	1
Number of collective bargaining agreements at locations with multiple CBAs | unit	2	2
Number of collective bargaining agreements that expire in calendar 2012 | agreement	1
Employer matching contribution percentage of first 5 percent of employee contribution	100.00%
Defined contribution plan employer matching contribution percentage of employee contribution	5.00%	5.00%
Employer discretionary contribution amount | $	$ 2,778