Shareholders' Equity (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020 vote classOfCommonStock $ / shares shares	Dec. 31, 2019 $ / shares shares	Aug. 31, 2006 shares
Class of Stock [Line Items]
Number of classes of common stock | classOfCommonStock	2
Common Class A
Class of Stock [Line Items]
Number of votes entitled to shareholders per share of common stock | vote	1
Common stock, par or stated value per share (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Common stock, capital shares reserved for future issuance (in shares)		1,600,000
Number of shares authorized to be repurchased (in shares)			2,000,000
Purchases of common stock (in shares)	0
Common Class A | IPO | Number of Shares Reduced
Class of Stock [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		1,600,000
Common Class B
Class of Stock [Line Items]
Number of votes entitled to shareholders per share of common stock | vote	10
Common stock, par or stated value per share (in dollars per share) | $ / shares	$ 0.001	$ 0.001