The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

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Debt (Details Textual) - USD ($) $ in Thousands						1 Months Ended	3 Months Ended		6 Months Ended
Debt (Details Textual) - USD ($) $ in Thousands	Aug. 28, 2018	Jul. 19, 2018	Jul. 16, 2018	Jun. 29, 2018	Dec. 05, 2017	Mar. 31, 2018	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Aug. 14, 2018	Jul. 10, 2018	Jun. 15, 2018	Nov. 19, 2015
Debt Instrument [Line Items]
Document Period End Date									Sep. 29, 2018
Gain (Loss) on Extinguishment of Debt							$ 48,800		$ 82,200
Proceeds from debt issuances (Note 6)									631,300	$ 0
Long-term debt						$ 983,290	$ 735,098		$ 735,098
6.75% Senior Notes due 2023
Debt Instrument [Line Items]
Debt Instrument, Face Amount														$ 450,000
Stated Interest Rate							6.75%		6.75%
Repayments of Senior Debt		$ 15,300		$ 429,200		$ 5,500
Senior notes, redemption percentage, actual		100.00%		106.75%		107.50%
Long-term debt						$ 444,464	$ 0		$ 0
7.00% Senior Notes due 2025
Debt Instrument [Line Items]
Debt Instrument, Face Amount														$ 550,000
Stated Interest Rate							7.00%		7.00%
Repayments of Senior Debt	$ 136,400		$ 300,000			$ 1,500
Senior notes, redemption percentage, actual	110.00%		109.63%			109.50%
Tender Offer Cap	$ 140,000										$ 130,000	$ 300,000	$ 150,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed									35.00%
Debt Instrument, Redemption Price, Percentage									107.00%
Long-term Debt, Fair Value						$ 596,500	$ 120,000		$ 120,000
Long-term debt						548,500	112,110		112,110
Senior notes
Debt Instrument [Line Items]
Interest Expense, Borrowings							10,900	$ 17,300	28,000	34,600
Interest Costs Capitalized							1,800	$ 3,200	5,300	8,800
Interest Paid							7,300		41,500	$ 34,400
5.5% Senior Notes due 2026
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 500,000
Stated Interest Rate			5.50%
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed			35.00%
Debt Instrument, Redemption Price, Percentage			105.50%
Long-term Debt, Fair Value							641,025		641,025
Long-term debt						$ 0	630,000		630,000
Bank of America Syndicate [Member] \| Senior Delayed Draw Term Loan [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Senior Delayed Draw Term Loan, Maximum Amount					$ 400,000
Proceeds from debt issuances (Note 6)					100,000
Bank of America Syndicate [Member] \| Revolving Credit Facility [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Proceeds from Lines of Credit							0
Line of Credit Facility, Maximum Borrowing Capacity					300,000
Line of Credit Facility, Maximum amount of increase that may be requested					300,000
Long-term debt							$ 0		$ 0
Bank of America Syndicate [Member] \| Standby Letters of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					25,000
Bank of America Syndicate [Member] \| Swingline Loan [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					$ 10,000
Minimum [Member] \| 5.5% Senior Notes due 2026
Debt Instrument [Line Items]
Debt, Interest Rate, Default Increase, Percentage			0.25%
Each additional 90-day period \| 5.5% Senior Notes due 2026
Debt Instrument [Line Items]
Debt, Interest Rate, Default Increase, Percentage			0.25%
Maximum [Member] \| 5.5% Senior Notes due 2026
Debt Instrument [Line Items]
Debt, Interest Rate, Default Increase, Percentage			1.00%