Summary of Significant Accounting Policies (Net Income Per Share) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Basic (in shares)	51,016	56,205	58,066
Diluted (in shares)	51,733	57,037	58,947
Employee Stock Option [Member]
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Effect of dilution (in shares)	0	14	15
Restricted Stock Units (RSUs) [Member]
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Effect of dilution (in shares)	717	818	866