Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Quoted prices In active markets for identical assets (Level 1) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	$ 701,146	$ 846,369
Liabilities [Abstract]
Fair value of financial liabilities measured on recurring basis	0	0
Significant other observable inputs (Level 2) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	93,095	0
Liabilities [Abstract]
Fair value of financial liabilities measured on recurring basis	0	0
Significant unobservable inputs (Level 3) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0	0
Liabilities [Abstract]
Fair value of financial liabilities measured on recurring basis	4,759	4,747
Total [Member]
ASSETS
Fair value of financial assets measured on recurring basis	794,241	846,369
Liabilities [Abstract]
Fair value of financial liabilities measured on recurring basis	4,759	4,747
Money market funds [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	698,750	843,390
Money market funds [Member] | Significant other observable inputs (Level 2) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0	0
Money market funds [Member] | Significant unobservable inputs (Level 3) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0	0
Money market funds [Member] | Total [Member]
ASSETS
Fair value of financial assets measured on recurring basis	698,750	843,390
Guaranteed investment certificates original maturities of less than three months [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Guaranteed investment certificates original maturities of less than three months [Member] | Significant other observable inputs (Level 2) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	18,815
Guaranteed investment certificates original maturities of less than three months [Member] | Significant unobservable inputs (Level 3) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Guaranteed investment certificates original maturities of less than three months [Member] | Total [Member]
ASSETS
Fair value of financial assets measured on recurring basis	18,815
Guaranteed investment certificates original maturities of three months or more [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Guaranteed investment certificates original maturities of three months or more [Member] | Significant other observable inputs (Level 2) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	49,712
Guaranteed investment certificates original maturities of three months or more [Member] | Significant unobservable inputs (Level 3) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Guaranteed investment certificates original maturities of three months or more [Member] | Total [Member]
ASSETS
Fair value of financial assets measured on recurring basis	49,712
Commercial paper [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Commercial paper [Member] | Significant other observable inputs (Level 2) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	14,752
Commercial paper [Member] | Significant unobservable inputs (Level 3) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Commercial paper [Member] | Total [Member]
ASSETS
Fair value of financial assets measured on recurring basis	14,752
Bonds [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Bonds [Member] | Significant other observable inputs (Level 2) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	9,816
Bonds [Member] | Significant unobservable inputs (Level 3) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0
Bonds [Member] | Total [Member]
ASSETS
Fair value of financial assets measured on recurring basis	9,816
Equity securities [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	2,396	2,979
Equity securities [Member] | Significant other observable inputs (Level 2) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0	0
Equity securities [Member] | Significant unobservable inputs (Level 3) [Member]
ASSETS
Fair value of financial assets measured on recurring basis	0	0
Equity securities [Member] | Total [Member]
ASSETS
Fair value of financial assets measured on recurring basis	2,396	2,979
Acquisition-related contingent consideration - short-term [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - short-term	0	0
Acquisition-related contingent consideration - short-term [Member] | Significant other observable inputs (Level 2) [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - short-term	0	0
Acquisition-related contingent consideration - short-term [Member] | Significant unobservable inputs (Level 3) [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - short-term	3,877	3,878
Acquisition-related contingent consideration - short-term [Member] | Total [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - short-term	3,877	3,878
Acquisition-related contingent consideration - long-term [Member] | Quoted prices In active markets for identical assets (Level 1) [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - long-term	0	0
Acquisition-related contingent consideration - long-term [Member] | Significant other observable inputs (Level 2) [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - long-term	0	0
Acquisition-related contingent consideration - long-term [Member] | Significant unobservable inputs (Level 3) [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - long-term	882	869
Acquisition-related contingent consideration - long-term [Member] | Total [Member]
Liabilities [Abstract]
Acquisition-related contingent consideration - long-term	$ 882	$ 869