Senior Unsecured Notes (Details) - USD ($)
 3 Months Ended 9 Months Ended
Sep. 19, 2016
Sep. 30, 2016
Sep. 30, 2016
Dec. 31, 2015
Debt Instrument [Line Items]        
Principal balance outstanding   $ 2,455,309,000 $ 2,455,309,000 $ 2,145,393,000
Loss from extinguishment of debt, net   19,302,000 6,882,000  
Total senior unsecured notes, net   $ 2,474,148,000 2,474,148,000 2,154,920,000
Repayments of senior unsecured notes     $ 314,755,000  
5.800% Senior Unsecured Notes, Due January 15, 2016 [Member]        
Debt Instrument [Line Items]        
Interest rate of senior unsecured notes   5.80% 5.80%  
Maturity date of the senior unsecured notes     Jan. 15, 2016  
2.500% Senior Unsecured Notes Due December 15, 2017 [Member]        
Debt Instrument [Line Items]        
Interest rate of senior unsecured notes   2.50% 2.50%  
Maturity date of the senior unsecured notes     Dec. 15, 2017  
7.750% Senior Unsecured Notes, Due August 15, 2019 [Member]        
Debt Instrument [Line Items]        
Interest rate of senior unsecured notes   7.75% 7.75%  
Maturity date of the senior unsecured notes     Aug. 15, 2019  
4.500% Senior Unsecured Notes Due April 18, 2022 [Member]        
Debt Instrument [Line Items]        
Interest rate of senior unsecured notes   4.50% 4.50%  
Maturity date of the senior unsecured notes     Apr. 18, 2022  
3.150% Senior Unsecured Notes, Due May 15, 2023 [Member]        
Debt Instrument [Line Items]        
Interest rate of senior unsecured notes   3.15% 3.15%  
Maturity date of the senior unsecured notes     May 15, 2023  
Unsecured Note [Member]        
Debt Instrument [Line Items]        
Principal balance outstanding   $ 960,136,000 $ 960,136,000 1,275,000,000
Adjustment for unamortized debt discount   (5,013,000) (5,013,000) (6,156,000)
Unamortized deferred financing costs   (3,848,000) (3,848,000) (5,062,000)
Loss from extinguishment of debt, net   19,300,000 19,300,000  
Total senior unsecured notes, net   951,275,000 951,275,000 1,263,782,000
Face amount of senior unsecured notes $ 114,900,000      
Redemption percentage of notes 115.977%      
Repayments of senior unsecured notes $ 134,100,000      
Unsecured Note [Member] | 5.800% Senior Unsecured Notes, Due January 15, 2016 [Member]        
Debt Instrument [Line Items]        
Principal balance outstanding   $ 200,000,000 $ 200,000,000 200,000,000 [1]
Effective rate [1],[2]   5.806% 5.806%  
Interest rate of senior unsecured notes   5.80% 5.80%  
Maturity date of the senior unsecured notes     Jan. 15, 2016  
Unsecured Note [Member] | 2.500% Senior Unsecured Notes Due December 15, 2017 [Member]        
Debt Instrument [Line Items]        
Principal balance outstanding   $ 250,000,000 $ 250,000,000 250,000,000
Effective rate [2]   2.803% 2.803%  
Unsecured Note [Member] | 7.750% Senior Unsecured Notes, Due August 15, 2019 [Member]        
Debt Instrument [Line Items]        
Principal balance outstanding [3]   $ 135,136,000 $ 135,136,000 250,000,000
Effective rate [2],[3]   8.017% 8.017%  
Unsecured Note [Member] | 4.500% Senior Unsecured Notes Due April 18, 2022 [Member]        
Debt Instrument [Line Items]        
Principal balance outstanding   $ 300,000,000 $ 300,000,000 300,000,000
Effective rate [2]   4.612% 4.612%  
Unsecured Note [Member] | 3.150% Senior Unsecured Notes, Due May 15, 2023 [Member]        
Debt Instrument [Line Items]        
Principal balance outstanding   $ 275,000,000 $ 275,000,000 $ 275,000,000
Effective rate [2]   3.517% 3.517%  
[1] On January 15, 2016, the Company repaid these notes at their maturity using proceeds from a new unsecured term loan and borrowings under the Company's unsecured revolving credit facility.
[2] Includes the cost of terminated treasury lock agreements (if any), offering and other transaction costs and the discount/premium on the notes, as applicable.
[3] On September 19, 2016, the Company purchased $114.9 million principal amount of these notes pursuant to its tender offer. See summary above.