Stock-Based Compensation (Details) (USD $)	12 Months Ended				12 Months Ended					3 Months Ended	12 Months Ended			24 Months Ended	12 Months Ended			12 Months Ended			3 Months Ended	12 Months Ended							12 Months Ended							1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2006 Former senior executives item	Dec. 31, 2012 Stock options	Dec. 31, 2011 Stock options	Dec. 31, 2010 Stock options	Dec. 31, 2012 Stock options Maximum	Dec. 31, 2012 Stock options Acquisition Health Data Insights, Inc	Dec. 31, 2012 Restricted Stock Units	Dec. 31, 2012 Restricted Stock Units	Dec. 31, 2011 Restricted Stock Units	Dec. 31, 2010 Restricted Stock Units	Dec. 31, 2012 Restricted Stock Units	Dec. 31, 2012 NQs and RSUs	Dec. 31, 2012 Amended 2011 Stock Option and Stock Issuance Plan item	Dec. 31, 2012 Amended 2011 Stock Option and Stock Issuance Plan Stock options	Dec. 31, 2012 Amended 2011 Stock Option and Stock Issuance Plan Stock options Minimum	Dec. 31, 2012 Amended 2011 Stock Option and Stock Issuance Plan Stock options Maximum	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Stock options	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Stock options	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Stock options Minimum	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Stock options Maximum	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Restricted Stock Units	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Restricted Stock Units Minimum	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Restricted Stock Units Maximum	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Restricted Stock Awards	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Restricted Stock Awards Minimum	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Restricted Stock Awards Maximum	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Stock options and restricted units Director	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Stock options and restricted units Certain executive officers	Dec. 31, 2012 Fourth Amended and Restated 2006 Stock Plan Stock options and restricted units Employees	Dec. 31, 2012 1999 Long-Term Incentive Stock Plan Stock options	Dec. 31, 2012 Options Issued Outside the Plans Stock options	Sep. 30, 2006 Options Issued Outside the Plans Stock options Former senior executives	Jul. 31, 2007 Options Issued Outside the Plans Stock options Walter D. Hosp, Chief Financial Officer
Stock-based compensation
Vesting period									4 years									1 month	4 years				1 year	4 years		1 year	5 years		1 year	5 years	1 year
Stock-based compensation expense recognized related to stock compensation plans	$ 9,100,000	$ 8,400,000	$ 7,500,000		$ 7,300,000	$ 5,600,000	$ 6,300,000				$ 1,000,000	$ 2,000,000	$ 400,000
Benefit recognized as a result of cancellation of awards					2,500,000									2,400,000	4,900,000
Number of options outstanding (in shares)					4,604,000	6,296,000											491,606				3,370,734	3,370,734												539,317	205,000
Number of separate equity programs																2
Number of shares authorized																836,122				18,000,000
Number of shares of common stock available for grant																187,092				9,138,398
Term of stock options, Maximum								10 years
Number of shares granted																					951,912	958,746														25,000	180,000
Awards other than stock options and SARs, number of shares counted for every one share awarded under plan limit																				1.85
Maximum term of stock option (in years)																						P7Y
Granted (in shares)										123,838	125,000														128,461
Increments by which one half of employee stock options vest																																0.3333	0.3333
Outstanding equity instruments other than option										237,000	237,000	509,000		237,000											236,620			191,880
Number of former senior executives				4
Weighted-average grant-date fair value per share of the stock options granted					$ 9.35	$ 8.47	$ 7.08
Exercise price range, upper limit																					$ 27.86
Exercise price range, lower limit																					$ 27.79
Additional disclosures
Common stock issued upon exercise of stock options (in shares)					1,673,000	2,100,000	2,700,000
Proceeds from exercise of stock options	11,973,000	12,744,000	9,128,000		12,000,000	12,700,000	9,100,000
Tax benefit from exercise of stock options	$ 12,433,000	$ 12,051,000	$ 12,581,000