Share-Based and Other Deferred Compensation - Additional information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended				12 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended																							1 Months Ended	12 Months Ended	3 Months Ended		12 Months Ended		12 Months Ended			3 Months Ended				3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011 Employee	Dec. 31, 2012 2006 Stock Incentive Plan	Dec. 31, 2011 2006 Stock Incentive Plan	Dec. 31, 2011 IPO Event-Based Awards	Dec. 31, 2012 IPO Event-Based Awards	Dec. 31, 2012 Equity Grants	Dec. 31, 2011 Equity Grants	Aug. 19, 2011 Class A	Dec. 31, 2012 Class A 2006 Stock Incentive Plan	Dec. 31, 2012 Class A IPO Event-Based Awards Restricted Stock Units (RSUs)	Dec. 31, 2012 Lp Units	Dec. 31, 2011 Lp Units	Dec. 31, 2010 Lp Units	Dec. 31, 2012 Acquisition-Related	Dec. 31, 2011 Acquisition-Related	Dec. 31, 2012 Acquisition-Related Unvested Acquisition-Related Equity Awards	Dec. 31, 2012 Acquisition-Related Unvested Acquisition-Related Equity Awards Lexicon Deferred Compensation [Member] Y	Dec. 31, 2011 Acquisition-Related Unvested Acquisition-Related Equity Awards Lexicon Deferred Compensation [Member]	Dec. 31, 2011 Acquisition-Related Class A	Dec. 31, 2012 Twenty Twelve Equity Grants Equity Grants	Dec. 31, 2012 Twenty Twelve Equity Grants Equity Grants Minimum	Dec. 31, 2012 Twenty Twelve Equity Grants Equity Grants Maximum	Dec. 31, 2012 Twenty Twelve Equity Grants Equity Grants Restricted Stock Units (RSUs)	Dec. 31, 2012 Twenty Twelve Equity Grants Service-Based Awards [Member]	Dec. 31, 2011 2011 Equity Grants Equity Grants	Dec. 31, 2011 2011 Equity Grants Equity Grants Minimum	Dec. 31, 2011 2011 Equity Grants Equity Grants Maximum	Dec. 31, 2011 2011 Equity Grants Equity Grants Restricted Stock Units (RSUs)	Dec. 31, 2010 2010 Equity Grants Equity Grants	Dec. 31, 2010 2010 Equity Grants Equity Grants Minimum	Dec. 31, 2010 2010 Equity Grants Equity Grants Maximum	Sep. 30, 2010 2010 Equity Grants Equity Grants Restricted Stock Units (RSUs)	Dec. 31, 2010 2010 Equity Grants Equity Grants Restricted Stock Units (RSUs)	Mar. 31, 2012 Deferred Cash Program Y	Mar. 31, 2011 Deferred Cash Program Y	Dec. 31, 2012 Deferred Cash Program	Dec. 31, 2011 Deferred Cash Program	Dec. 31, 2012 Other Share Based Awards	Dec. 31, 2011 Other Share Based Awards	Dec. 31, 2010 Other Share Based Awards	Mar. 31, 2013 Other Share Based Awards Subsequent Event	Mar. 31, 2013 Other Share Based Awards Subsequent Event President and Chief Executive Officer	Mar. 31, 2013 Other Share Based Awards Subsequent Event President And Chief Executive Officer Y	Mar. 31, 2013 Other Share Based Awards Subsequent Event President And Chief Executive Officer Minimum	Mar. 31, 2013 Other Deferred Cash Subsequent Event Y
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested LP units												13,548
Unvested units												9,589
Lp Units Convertible Conversion Ratio	1											1
Amortization of LP Units												$ 20,971	$ 22,189	$ 20,060
Total compensation expense												19,350					23,381	385							104,967												7,316
Weighted-average period over which the compensation cost is expected to be recognized												12 months					30 months	8 months							20 months												28 months
Acquisition Related Share Issuance									28											1,883
Compensation expense related to acquisition related awards															18,749	6,621
Compensation expense related to deferred cash consideration															7,216	2,455
Grant of Acquisition related Deferred compensation																		1,892
Deferred compensation, vesting period																		2
Expense related to Acquisition related Deferred compensation																		875	413
Stock Authorized under plan										20,000
Shares available to be granted in future			4,667	7,434
Original Grant Of Event Based Awards											2,286
RSUs convertible into Class A common Stock ratio											1
Unvested event based awards						12	7,972	8,351
Vesting Of Event Based Awards					546
Expense Related To Vesting Of Event Based Awards					11,467
Event Based Awards Forfeited					27		393														256					76				32			275
Deferred cash awards granted																																			3,926	9,153										10,300
Deferred compensation, vesting period, years																																			4	4
Compensation expense related to deferred compensation program																																					4,210	1,938
Stock issued during period							3,312																	3,163					2,273					1,474								2,000	50
Service based awards, grant date fair value																						$ 22.62	$ 29.19				$ 21.93	$ 36.41			$ 23.31	$ 35.79
Vested units							3,298														1,760					1,552				1,457
Compensation expense related to Service-based Award																					62,840					47,299				35,347
Unvested units																													97
Vested units																													37
Share based awards reclassified from additional paid-in-capital to other current liabilities		2,828
Grant date fair value																																	3,226
Total compensation expense																																	352
Income tax benefit related to share-based compensation arrangements																																							26,773	19,423	9,392
Stock price per share																																													$ 45.00
Number of consecutive trading days																																												20 days
Awards, vesting period, in years																																												4		2
Separation expense to certain employees																																							7,273
Cash distribution for separation benefit																																							5,135
Number of employees with modified equity based compensation awards		4
Incremental Compensation Expense From Modifications		$ 4,261