Restricted Cash (Narrative) (Details) - USD ($)		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Aug. 15, 2016	Dec. 31, 2015	Sep. 28, 2012
Restricted Cash And Cash Equivalents Items [Line Items]
Total restricted cash		$ 555,706,000			$ 28,580,000
Debt instrument, principal balance		9,140,000,000			8,555,000,000
Accrued interest	[1]	(31,887,000)	$ (13,994,000)
Surety, payment and performance bonds		39,000,000			38,600,000
Collateral payment for performance bonds		500,000			700,000
Collateral related to workers compensation policy		2,500,000			2,500,000
5.625% Senior Notes [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Debt instrument, principal balance		500,000,000			$ 500,000,000
Debt call premium		14,100,000
Accrued interest		$ 14,100,000
Debt instrument stated percentage		5.625%		5.625%		5.625%
Escrow Account For Payment Of 5.625% Senior Notes [Member] | Restricted Cash - Current Asset [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Total restricted cash		$ 528,128,000

[1] $14.1 million of accrued interest on the 5.625% Senior Notes is included in accrued interest above.