Debt and Borrowings (Narrative) (Details)		6 Months Ended
	Dec. 12, 2014 USD ($)	Dec. 31, 2016 GBP (£)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 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	4.00
Leverage ratio	3.50
Consolidated leverage ratio	4.0
Credit Agreement borrowings payable to banks [Member]
Line of Credit Facility [Line Items]
Revolving credit facility	$ 1,000,000,000
Letters of credit outstanding			$ 783,911,000
Remaining borrowing capacity			$ 209,909,000
Long-term debt, weighted average interest rate		1.98%	1.98%	1.98%
Credit Agreement borrowings payable to banks [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Unused capacity, commitment fee, percentage	0.20%
Credit Agreement borrowings payable to banks [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Unused capacity, commitment fee, percentage	0.30%
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Letters of credit outstanding			$ 6,180,000
Eurocurrency Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	0.875%
Eurocurrency Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	1.70%
Base Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	0.00%
Base Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	0.70%
Tilda short-term borrowing arrangements [Member]
Line of Credit Facility [Line Items]
Revolving credit facility | £		£ 52,000,000
Debt instrument, term		6 months
Short-term debt, weighted average interest rate		2.80%	2.80%	2.80%
Mona [Member]
Line of Credit Facility [Line Items]
Revolving credit facility | €				€ 12,500,000
Short-term debt, weighted average interest rate		1.10%	1.10%	1.10%