Nature of Operations and Summary of Significant Accounting Policies (Basis of Presentation and Principles of Consolidation) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Reclassification out of trade receivables, net	$ (108,381)	$ (103,091)	$ (86,268)	$ (79,102)	$ (98,361)	$ (112,309)	$ (76,132)	$ (79,358)
Reclassification into prepaid expenses and other current assets	11,345	14,086	16,412	17,379	15,396	12,595	14,569	14,615
Restatement Impacts
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Reclassification out of trade receivables, net	5,400	2,179	2,446	2,768	2,460	351	411	191
Reclassification into prepaid expenses and other current assets	(11,757)	$ (7,505)	$ (6,723)	$ (6,605)	(6,936)	$ (5,668)	$ (3,888)	$ (2,655)
Prior period adjustment to conform to current period presentation | Restatement Impacts
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Reclassification out of trade receivables, net					$ 9,500
Reclassification into prepaid expenses and other current assets	$ 9,500