Debt and Borrowings (Narrative) (Details)		12 Months Ended
	Dec. 12, 2014 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2017 GBP (£)	Jun. 30, 2017 USD ($)	Jun. 30, 2017 EUR (€)
Line of Credit Facility [Line Items]
Line of credit potential incremental borrowing capacity post-amendment	$ 350,000,000
Revolving credit facility expiration date	Dec. 12, 2019
Interest coverage ratio	4.0
Leverage ratio	3.5
Consolidated leverage ratio	4.0
Interest paid		$ 18,873,000	$ 24,288,000	$ 22,865,000
Credit Agreement borrowings payable to banks
Line of Credit Facility [Line Items]
Revolving credit facility	$ 1,000,000,000
Borrowing under letters of credit						$ 733,715,000
Remaining borrowing capacity						$ 260,105,000
Long-term debt, weighted average interest rate					2.93%	2.93%	2.93%
Letter of credit
Line of Credit Facility [Line Items]
Borrowing under letters of credit						$ 6,180,000
Tilda short-term borrowing arrangements
Line of Credit Facility [Line Items]
Revolving credit facility | £					£ 52,000,000
Debt instrument, term		6 months
Short-term debt, weighted average interest rate					2.70%	2.70%	2.70%
Line of Credit
Line of Credit Facility [Line Items]
Revolving credit facility | €							€ 12,500,000
Mona
Line of Credit Facility [Line Items]
Short-term debt, weighted average interest rate					1.10%	1.10%	1.10%
Minimum | Credit Agreement borrowings payable to banks
Line of Credit Facility [Line Items]
Unused capacity, commitment fee, percentage	0.20%
Minimum | Eurocurrency Rate
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	0.875%
Minimum | Base Rate
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	0.00%
Maximum | Credit Agreement borrowings payable to banks
Line of Credit Facility [Line Items]
Unused capacity, commitment fee, percentage	0.30%
Maximum | Eurocurrency Rate
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	1.70%
Maximum | Base Rate
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	0.70%