Summary of Significant Accounting Policies (Change in Accounting Method) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Change in Accounting Method [Line Items]
Accrued liabilities and other liabilities	$ 598,109	$ 513,970
Other assets	$ (743,686)	(650,266)
Accrued Expenses and Other Liabilities
Change in Accounting Method [Line Items]
Accrued liabilities and other liabilities		(28,700)
Other Assets
Change in Accounting Method [Line Items]
Other assets		$ 28,700