Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary Of Significant Accounting Policies [Line Items]
Amortization expense related to software costs	$ 40,889,000	$ 33,728,000	$ 32,757,000
Cash, uninsured amount	394,597,000
Provisions for doubtful accounts	938,000	404,000	1,757,000
Net foreign exchange losses	1,400,000	400,000	400,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Frequency period of major product upgrades (months)	12 months
Property and equipment, estimated useful lives (years)	1 year
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Frequency period of major product upgrades (months)	18 months
Property and equipment, estimated useful lives (years)	40 years
Credit Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Uninsured cash balances held outside U.S.	164,500,000
Cash equivalent balances with U.S. financial institution	296,300,000
FDIC [Member] | Credit Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash accounts held in U.S. banks	250,000
SIPC [Member] | Credit Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
SIPC insurance limit per customer	500,000
Acquired And Internally Developed Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated life of capitalized software products, (years)	3 years
Amortization expense related to software costs	$ 40,889,000	$ 33,728,000	$ 32,757,000
Money Market Funds [Member] | Cash and Cash Equivalents [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Risk, Percentage	98.00%	100.00%