Incentive Plans - Additional Information (Detail)	1 Months Ended	12 Months Ended						12 Months Ended								12 Months Ended						12 Months Ended
	Feb. 28, 2013 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)		Dec. 31, 2011 USD ($)		Aug. 30, 2013	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2013 2012 Long-Term Plan [Member]	Dec. 31, 2013 2012 Long-Term Plan and the 2007 Long-Term Plan [Member]	Dec. 31, 2013 Director Plan [Member]	Dec. 31, 2013 Stock Options [Member]	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2013 Time-Lapse Restricted Stock and Restricted Stock Units [Member] USD ($)	Dec. 31, 2012 Time-Lapse Restricted Stock and Restricted Stock Units [Member] USD ($)	Dec. 31, 2011 Time-Lapse Restricted Stock and Restricted Stock Units [Member] USD ($)	Dec. 31, 2013 Phantom Units [Member] USD ($)	Dec. 31, 2012 Phantom Units [Member] USD ($)	Aug. 30, 2013 Phantom Units [Member]	Dec. 31, 2013 Performance Based Restricted Stock [Member]	Dec. 31, 2013 Performance Based Restricted Stock [Member] Maximum [Member] USD ($)	Dec. 31, 2012 Performance Based Restricted Stock [Member] Maximum [Member] USD ($)	Dec. 31, 2011 Performance Based Restricted Stock [Member] Maximum [Member] USD ($)	Dec. 31, 2013 Performance Based Restricted Stock [Member] Minimum [Member] USD ($)	Dec. 31, 2012 Performance Based Restricted Stock [Member] Minimum [Member] USD ($)	Dec. 31, 2011 Performance Based Restricted Stock [Member] Minimum [Member] USD ($)	Dec. 31, 2013 Employee Stock Purchase Plan (ESPP) [Member] USD ($)	Dec. 31, 2012 Employee Stock Purchase Plan (ESPP) [Member] USD ($)	Dec. 31, 2011 Employee Stock Purchase Plan (ESPP) [Member] USD ($)	Dec. 31, 2013 Savings Related Share Option Plan (SOP) [Member] USD ($)	Dec. 31, 2012 Savings Related Share Option Plan (SOP) [Member] USD ($)	Dec. 31, 2011 Savings Related Share Option Plan (SOP) [Member] USD ($)	Dec. 31, 2013 Savings Related Share Option Plan (SOP) [Member] Maximum [Member] GBP (£)	Dec. 31, 2013 Savings Related Share Option Plan (SOP) [Member] Minimum [Member] GBP (£)	Dec. 31, 2013 Savings Related Share Option Plan (SOP) [Member] SOP plans with holding periods ending in April 2011 [Member] USD ($)	Dec. 31, 2013 Savings Related Share Option Plan (SOP) [Member] SOP plans with holding periods ending in May 2012 [Member] USD ($)	Dec. 31, 2013 Performance Units [Member] USD ($)	Dec. 31, 2012 Performance Units [Member] USD ($)	Dec. 31, 2011 Performance Units [Member] USD ($)
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Long term plan expiration year									2022
Maximum number of shares available for issuance									8,700,000																				980,000
Maximum number of shares available for issuance, annual rate									1.00%
Number of shares remained available									7,135,000																				286,941
Unvested share-based compensation arrangements, compensation costs to be expensed		$ 59,505,000
Unvested share-based compensation arrangements, number of years compensation costs to be expensed		2 years
Proceeds from exercise of stock options and employee stock purchase plans		3,409,000	12,324,000	[1]	15,551,000	[1]
Income tax benefits realized for the tax deductions from option exercises		7,435,000	5,920,000		8,775,000
Option granted to date, term of years								7 years		7 years
Employee stock purchase plan, vesting scheme										Under the 2012 Long-Term Plan and the 2007 Long-Term Plan, one-half of each grant is generally exercisable after two years and the remainder after three years.	Under the Director Plan, one-third of each grant is exercisable after each of the first three years.
Stock-based compensation, fair value assumption model												Black-Scholes pricing model										Monte Carlo valuation model
Total intrinsic value of options exercised		25,284,000	17,197,000		28,145,000
Reduction in stock option exercise price	$ 2.50
Income statement effect of reduced exercise price	6,454,000
Percentage increase in number of outstanding stock options							10.70%
Percentage decrease in exercise price of stock options							10.70%
Price at which liability calculated		$ 64.88
Granted restricted stock, valuation																$ 69.67	$ 59.33	$ 52.66					$ 68.01	$ 63.64	$ 64.89	$ 39.50	$ 54.90	$ 38.94
Percentage increase in number of outstanding stock units																10.70%					10.70%
Compensation expenses																			2,063,000	305,000									143,000	272,000	328,000	0	110,000	538,000					2,062,000	2,665,000	871,000
Percentage of targeted amounts paid in cash and awards based on achievement, minimum																																							0.00%	0.00%	0.00%
Percentage of targeted amounts paid in cash and awards based on achievement, maximum																																							200.00%	200.00%	200.00%
Performance units outstanding		6,006,585										6,006,585	5,907,359	5,434,228	5,302,384																								0
Salary that can be withheld by eligible employee for stock purchase																													10.00%
Stock purchase price, percentage of the fair value of the stock																													90.00%			90.00%
Employee Stock purchase plan, termination date																													The ESPP will terminate on the earlier of the date that employees have purchased all 980,000 authorized shares or June 30, 2017.
Employee stock purchases, shares																													16,020	24,418	28,555
Employee stock purchases, per share																													$ 54.14	$ 48.54	$ 55.28
Compensation costs estimation																													Compensation costs related to the ESPP are estimated based on the value of the 10% discount and the fair value of the option that provides for the refund of participant withholdings			Compensation costs related to the SOP plan were estimated based on the value of the 10% discount and the fair value of the option that allowed the employee to receive a repayment of withholdings plus credited interest.
Fair value per share issued under ESPP																													$ 6.72	$ 7.30	$ 8.60
Monthly salary that can be withhold by eligible employee for stock purchase																																			250	5
Fair value per share of SOP plans																																					$ 23.77	$ 22.85
Compensation expense for incentive plans		$ 53,250,000	$ 32,417,000		$ 33,035,000

[1] Reclassified to conform to current presentation.