Debt - Carrying Amount and Fair Value of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jun. 30, 2017
Publicly Traded Debt | Carrying Amount
Debt Instrument [Line Items]
Debt	$ 8,737,229	$ 9,448,274
Publicly Traded Debt | Fair Value
Debt Instrument [Line Items]
Debt	8,499,644	9,660,353
Non-Publicly Traded Debt | Carrying Amount
Debt Instrument [Line Items]
Debt	986,868	2,004,111
Non-Publicly Traded Debt | Fair Value
Debt Instrument [Line Items]
Debt	$ 911,011	$ 1,863,095