Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Apr. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2018
Income Taxes [Line Items]
Income taxes payable	$ 160,427			$ 49,881		$ 49,881		$ 160,427
Income taxes paid						192,497	$ 51,456
Income tax expense (benefit)				$ 21,634	$ 132,238	54,778	$ 154,599
Tax Year 2018 [Member] | Scenario, Plan [Member]
Income Taxes [Line Items]
Income tax expense (benefit)								$ 138,000
Income tax expense from transition tax						$ 1,200
Australian Taxation Office [Member]
Income Taxes [Line Items]
Tax liabilities related to assessments			$ 151,700
Interest related to assessments			$ 38,400
Percentage of penalties on additional income tax	50.00%
Penalties related to assessments	$ 75,900
Income taxes paid		$ 75,900
Australian Taxation Office [Member] | Minimum [Member]
Income Taxes [Line Items]
Tax year under audit			2009			2014
Australian Taxation Office [Member] | Maximum [Member]
Income Taxes [Line Items]
Tax year under audit			2013			2017