v3.8.0.1
Debt and Credit Facility Credit Facility (Details)
 1 Months Ended 3 Months Ended 6 Months Ended
Feb. 28, 2017
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Nov. 07, 2017
USD ($)
Jun. 30, 2017
USD ($)
tranche
Mar. 31, 2017
USD ($)
Line of Credit Facility [Line Items]                
Interest coverage ratio   3.50   3.50        
Repayments of lines of credit [1]       $ 113,000,000 $ 951,500,000      
Debt issuance costs $ 33,700,000 $ 43,000,000   $ 43,000,000       $ 46,800,000
Credit Facility               $ 0
Debt instrument, description of variable rate basis       the highest of JPMorgan Chase Bank, N.A.'s prime rate, the federal funds rate plus a margin equal to 0.50% and the adjusted LIBOR rate for a 1-month interest period plus a margin equal to 1.00%        
Interest expense   $ 49,459,000 $ 35,126,000 $ 98,949,000 69,542,000      
Revolving credit facility                
Line of Credit Facility [Line Items]                
Credit agreement maximum borrowing amount             $ 2,774,000,000.000  
Number of commitment tranches | tranche             2  
Credit agreement, total leverage ratio, maximum   5.00   5.00       5.00
Credit Agreement, total consolidated debt, maximum   $ 700,000,000   $ 700,000,000        
Credit agreement, total leverage ratio, temporary maximum allowed, first four quarters   5.50   5.50        
Credit agreement, total leverage ratio, temporary maximum allowed, next three quarters   5.25   5.25        
Credit agreement, senior leverage ratio, maximum   3.50   3.50        
Credit agreement, senior leverage ratio, minimum to obtain additional funding   2.50   2.50        
Repayments of lines of credit 1,682,500,000              
Debt issuance costs $ 2,100,000              
Credit Facility   $ 0   $ 0        
Period for leverage ratio to determine interest rate spread       preceding four fiscal quarters        
Interest expense   $ 2,300,000 $ 12,000,000 $ 5,000,000 $ 23,600,000      
Interest rate spread on overdue principal in event of default (percentage)   2.00%   2.00%        
Interest rate spread on overdue amounts in event of default (percentage)   2.00%   2.00%        
Revolving credit facility | 2020 Tranche                
Line of Credit Facility [Line Items]                
Credit agreement maximum borrowing amount   $ 2,727,300,000.0   $ 2,727,300,000.0        
Revolving credit facility | Debt instrument interest rate option 2                
Line of Credit Facility [Line Items]                
Debt instrument, description of variable rate basis       adjusted LIBOR rate (based on one, two, three, or six-month interest periods)        
Foreign line of credit                
Line of Credit Facility [Line Items]                
Credit agreement maximum borrowing amount   125,000,000   $ 125,000,000        
Standby letters of credit                
Line of Credit Facility [Line Items]                
Credit agreement maximum borrowing amount   25,000,000   25,000,000        
Line of credit facility swingline loan sublimit                
Line of Credit Facility [Line Items]                
Credit agreement maximum borrowing amount   $ 25,000,000   $ 25,000,000        
Minimum | Revolving credit facility | Debt instrument interest rate option 1                
Line of Credit Facility [Line Items]                
Spread on variable rate (percentage)       0.25%        
Maximum | Revolving credit facility | Debt instrument interest rate option 1                
Line of Credit Facility [Line Items]                
Spread on variable rate (percentage)       1.25%        
Maximum | Revolving credit facility | Debt instrument interest rate option 2                
Line of Credit Facility [Line Items]                
Spread on variable rate (percentage)       2.25%        
Subsequent Event | Revolving credit facility | 2020 Tranche                
Line of Credit Facility [Line Items]                
Credit agreement maximum borrowing amount           $ 2,822,000,000.000    
[1] During the six months ended September 30, 2017, the Company issued $111.3 million principal amount of 2017 Junior Notes and 3.2 million shares of common stock in exchange for $111.3 million principal amount of 2007 Junior Notes. Refer to Note 13 Debt and Credit Facility for further discussion.