Debt (Details)
€ in Thousands, £ in Thousands, $ in Thousands
3 Months Ended 12 Months Ended
Jun. 30, 2015
USD ($)
Mar. 31, 2017
Mar. 31, 2020
USD ($)
Mar. 31, 2019
USD ($)
Feb. 27, 2017
GBP (£)
Feb. 27, 2017
USD ($)
Feb. 27, 2017
EUR (€)
Debt Instrument [Line Items]              
Senior Notes $ 350,000   $ 878,409 $ 884,967      
Long-term Debt, Current Maturities [1]     35,000        
Line of Credit Facility, Maximum Borrowing Capacity     1,000,000        
Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Net     (3,337) (3,619)      
Other Long-term Debt, Noncurrent     0 33      
Line of Credit Facility, Amount Outstanding     275,449 301,846      
Long-term Debt     1,153,858        
Long-term Debt     1,150,521 $ 1,183,227      
Long-term Debt, Maturities, Repayments of Principal in Year Two     0        
Long-term Debt, Maturities, Repayments of Principal in Year Three     366,449        
Long-term Debt, Maturities, Repayments of Principal in Year Four     0        
Long-term Debt, Maturities, Repayments of Principal after Year Five     752,409        
10 year maturity              
Debt Instrument [Line Items]              
Debt Instrument, Term 10 years 10 years          
12 year maturity              
Debt Instrument [Line Items]              
Debt Instrument, Term 10 years            
15 year maturity              
Debt Instrument [Line Items]              
Debt Instrument, Term 15 years            
Debt Instrument, Maturity Date, Description   P15Y          
Revolving Credit Facility [Member]              
Debt Instrument [Line Items]              
Line of Credit Facility, Maximum Borrowing Capacity     $ 500,000        
United States of America, Dollars              
Debt Instrument [Line Items]              
Senior Notes           $ 95,000  
United Kingdom, Pounds              
Debt Instrument [Line Items]              
Senior Notes | £         £ 75,000    
Euro Member Countries, Euro              
Debt Instrument [Line Items]              
Senior Notes | €             € 99,000
[1] This amount represents a senior note that matures in August 2020. In accordance with ASU 470-10-45, we have presented the note as a long-term liability based on our intention to refinance the note on a long-term basis under our credit facility