Long-Term Debt (Details) $ in Thousands				12 Months Ended
	Feb. 22, 2017 USD ($)	Oct. 24, 2016 USD ($)	Jun. 19, 2012 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)	Jul. 09, 2014 USD ($)	Oct. 16, 2013 USD ($)
Long-Term Debt
Face amount				$ 3,026,531	$ 2,936,244
Face amount, current portion				29,590	7,907
Face amount, long-term				2,996,941	2,928,337
Unamortized debt issuance costs				(33,458)	(15,500)
Book value				2,993,073	2,920,744
Book value, current				29,590	7,907
LONG-TERM DEBT, net of debt issuance costs and current maturities				2,963,483	2,912,837
Amortization of debt issuance costs				3,300	4,600	$ 3,000
Expected Future Amortization of Debt Issuance Costs [Abstract]
2018				6,452
2019				6,310
2020				5,337
2021				4,937
2022				4,355
Thereafter				6,067
Total				$ 33,458
Revolving Credit Facility
Expected Future Amortization of Debt Issuance Costs [Abstract]
Interest rate				3.72%
Revolving Credit Facility
Expected Future Amortization of Debt Issuance Costs [Abstract]
Maximum borrowing capacity				$ 1,765,000			$ 2,484,000
Increased borrowing capacity with the exercise of accordion feature				300,000
Deferred debt issuance costs				$ 9,700
Actual leverage ratio				4.65
Actual interest coverage ratio				3.20
Actual senior secured leverage ratio				0.54
Write off of debt issuance costs				$ 4,500
Revolving Credit Facility | Minimum
Expected Future Amortization of Debt Issuance Costs [Abstract]
Commitment fees charged on unused capacity				0.375%
Interest coverage ratio				2.75
Revolving Credit Facility | Maximum
Expected Future Amortization of Debt Issuance Costs [Abstract]
Commitment fees charged on unused capacity				0.50%
Leverage ratio				4.75
Revised senior secured leverage ratio				3.25
Senior secured leverage ratio				3.50
Revolving Credit Facility | Alternate base rate | Minimum
Expected Future Amortization of Debt Issuance Costs [Abstract]
Interest rate margin added to variable rate base				0.50%
Revolving Credit Facility | Alternate base rate | Maximum
Expected Future Amortization of Debt Issuance Costs [Abstract]
Interest rate margin added to variable rate base				1.75%
Revolving Credit Facility | LIBOR option
Expected Future Amortization of Debt Issuance Costs [Abstract]
Interest rate margin added to variable rate base				2.50%
Reference rate				0.97%
Revolving Credit Facility | LIBOR option | Minimum
Expected Future Amortization of Debt Issuance Costs [Abstract]
Interest rate margin added to variable rate base				1.50%
Revolving Credit Facility | LIBOR option | Maximum
Expected Future Amortization of Debt Issuance Costs [Abstract]
Interest rate margin added to variable rate base				2.75%
Revolving Credit Facility | Prime rate
Expected Future Amortization of Debt Issuance Costs [Abstract]
Interest rate margin added to variable rate base				1.50%
Reference rate				4.00%
Revolving Credit Facility | Expansion Capital Facility
Long-Term Debt
Face amount				$ 0	1,229,500
Unamortized debt issuance costs				0	0
Book value				0	1,229,500
Expected Future Amortization of Debt Issuance Costs [Abstract]
Maximum borrowing capacity				765,000
Revolving Credit Facility | Working Capital Facility
Long-Term Debt
Face amount				814,500	618,500
Unamortized debt issuance costs				0	0
Book value				814,500	618,500
Expected Future Amortization of Debt Issuance Costs [Abstract]
Maximum borrowing capacity				$ 1,000,000
Revolving Credit Facility | Letters of credit
Long-Term Debt
Fixed interest rate				2.50%
Senior Secured Notes
Long-Term Debt
Face amount				$ 250,000	250,000
Fixed interest rate			6.65%
Unamortized debt issuance costs				(4,559)	(3,166)
Book value				245,441	246,834
Expected Future Amortization of Debt Issuance Costs [Abstract]
Debt issued			$ 250,000
Repayments in semi-annual installments				$ 25,000
Covenant penalty rate				0.50%
Leverage ratio interest penalty rate				4.25
Leverage ratio additional interest penalty rate				4.50
Debt covenant terms, default trigger amount			$ 10,000
Percentage of aggregate principal amount held by trustee or holders to declare notes due and payable (at least)			50.10%
5.125% Senior Notes due 2019
Long-Term Debt
Face amount				$ 379,458	388,467
Fixed interest rate								5.125%
Unamortized debt issuance costs				(3,191)	(4,681)
Book value				376,267	383,786
Expected Future Amortization of Debt Issuance Costs [Abstract]
Debt issued								$ 400,000
Notes repurchased				9,009	11,533
Cash paid (excluding payments of accrued interest)				7,099	6,972
Gain on early extinguishment of debt				1,759	4,483
Write off of debt issuance costs				200	100
6.875% Senior Notes due 2021
Long-Term Debt
Face amount				367,048	388,289
Fixed interest rate									6.875%
Unamortized debt issuance costs				(5,812)	(7,545)
Book value				361,236	380,744
Expected Future Amortization of Debt Issuance Costs [Abstract]
Debt issued									$ 450,000
Notes repurchased				21,241	61,711
Cash paid (excluding payments of accrued interest)				14,094	36,449
Gain on early extinguishment of debt				6,748	24,049
Write off of debt issuance costs				400	1,200
7.50% Senior Notes due 2023
Long-Term Debt
Face amount				700,000
Fixed interest rate		7.50%
Unamortized debt issuance costs				(11,329)
Book value				688,671
Expected Future Amortization of Debt Issuance Costs [Abstract]
Debt issued		$ 700,000
Proceeds from unsecured notes payable		687,900
Senior notes purchaser's discount		10,500
Senior notes offering costs		$ 1,600
Redeemable percentage of principal amount		100.00%
6.125% Senior Notes due 2025
Long-Term Debt
Face amount				$ 500,000
Fixed interest rate	6.125%			6.125%
Unamortized debt issuance costs				$ (8,567)
Book value				491,433
Expected Future Amortization of Debt Issuance Costs [Abstract]
Debt issued	$ 500,000
Proceeds from unsecured notes payable	491,300
Senior notes purchaser's discount	7,500
Senior notes offering costs	$ 1,200
Other long-term debt
Long-Term Debt
Face amount				15,525	61,488
Unamortized debt issuance costs				0	(108)
Book value				15,525	$ 61,380
Letters of credit | Working Capital Facility
Expected Future Amortization of Debt Issuance Costs [Abstract]
Outstanding letters of credit				89,200
Non-compete
Long-Term Debt
Face amount				$ 8,900
Non-compete | Minimum
Long-Term Debt
Fixed interest rate				1.17%
Non-compete | Maximum
Long-Term Debt
Fixed interest rate				7.00%
Equipment loan
Long-Term Debt
Face amount				$ 6,600
Expected Future Amortization of Debt Issuance Costs [Abstract]
Gain on early extinguishment of debt				1,600
Write off of debt issuance costs				100
Repayments of debt				41,700
Other long term debt repayment penalty				$ 1,500
Equipment loan | Minimum
Long-Term Debt
Fixed interest rate				4.13%
Equipment loan | Maximum
Long-Term Debt
Fixed interest rate				7.10%
First 60 day period following the effectiveness deadline | Senior Notes 2023 and 2025
Expected Future Amortization of Debt Issuance Costs [Abstract]
Distribution rate, percentage increase	0.25%	0.25%