Recent Accounting Developments Recent Accounting Developments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in cash flows from operating activities reclassified to investing activities	$ (307,564)	$ (206,390)
Increase in cash flows from investing activities reclassified from operating activities	$ (92,927)	(1,443,167)
Accounting Standards Update 2016-15 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in cash flows from operating activities reclassified to investing activities		11,400
Increase in cash flows from investing activities reclassified from operating activities		$ 11,400