Summary of Significant Accounting Policies New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncement, Early Adoption [Line Items]
Unamortized Debt Issuance Expense	$ 34,030	$ 33,555	[1]
Other noncurrent assets	31,673	44,659
Assets, Noncurrent	152,374	234,199
Assets	5,621,643	6,483,145
Senior Notes	2,315,970	2,166,445	[1]
Liabilities, Noncurrent	3,466,717	3,411,830
Liabilities and Equity	$ 5,621,643	6,483,145
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Unamortized Debt Issuance Expense		33,600
Scenario, Previously Reported [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Other noncurrent assets		78,214
Assets, Noncurrent		267,754
Assets		6,516,700
Senior Notes		2,200,000
Liabilities, Noncurrent		3,445,385
Liabilities and Equity		$ 6,516,700

[1] Prior period amounts have been reclassified to conform to the current period presentation on the accompanying balance sheets. Please refer to the section Recently Issued Accounting Standards in Note 1 – Summary of Significant Accounting Policies for additional discussion.