Summary of Significant Accounting Policies (Narrative) (Details) - USD ($)		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		$ 0	$ 0
Capitalized costs		0	0	$ 0
Advertising costs		1,400,000	1,500,000	1,800,000
Foreign currency gains (losses)		600,000	(1,100,000)	(3,100,000)
Non-cash cumulative effect adjustment to retained earnings, net of tax		632,795,000	177,825,000	(9,233,000)	$ (53,842,000)
Reserve for contract assets and sales-type leases		3,700,000
Accounts receivable allowance for credit losses		6,800,000	3,600,000
Retained Earnings
Summary Of Significant Accounting Policies [Line Items]
Non-cash cumulative effect adjustment to retained earnings, net of tax		$ 2,175,595,000	1,595,648,000	$ 1,167,928,000	803,545,000
Accounting Standards Update 2016-13
Summary Of Significant Accounting Policies [Line Items]
Reserve for contract assets and sales-type leases	$ 2,300,000
Accounts receivable allowance for credit losses	200,000
Accounting Standards Update 2016-13 | Retained Earnings
Summary Of Significant Accounting Policies [Line Items]
Non-cash cumulative effect adjustment to retained earnings, tax	$ 600,000
Cumulative Effect, Period of Adoption, Adjustment
Summary Of Significant Accounting Policies [Line Items]
Non-cash cumulative effect adjustment to retained earnings, net of tax			(1,829,000)		(12,648,000)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Summary Of Significant Accounting Policies [Line Items]
Non-cash cumulative effect adjustment to retained earnings, net of tax			(1,829,000)		$ (12,648,000)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13 | Retained Earnings
Summary Of Significant Accounting Policies [Line Items]
Non-cash cumulative effect adjustment to retained earnings, net of tax			$ 1,800,000