Compensation Plans - Additional Information (Detail) (USD $)	12 Months Ended								0 Months Ended	12 Months Ended										12 Months Ended
	Dec. 31, 2013 plan	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Minimum New Employees [Member]	Dec. 31, 2013 Maximum	Dec. 31, 2013 Maximum New Employees [Member]	Dec. 31, 2013 Annual grants	Dec. 31, 2013 Retention Grant [Member]	May 15, 2012 Restricted Stock Units	Dec. 31, 2013 Restricted Stock Units	Dec. 31, 2012 Restricted Stock Units	Dec. 31, 2013 Restricted Stock Units Maximum Award Earned Based on Shareholder Return Relative to Predetermined Peer Group	Dec. 31, 2013 Restricted Stock Units Maximum Award Earned Based on Total Shareholder Return	Dec. 31, 2013 Restricted Stock	Dec. 31, 2012 Restricted Stock	Dec. 31, 2011 Restricted Stock	Dec. 31, 2013 Stock Options	Dec. 31, 2013 Amended And Restated 2003 Annual And Long -Term Incentive Plan	Dec. 31, 2013 Amended And Restated 2003 Annual And Long -Term Incentive Plan Maximum	Dec. 31, 2010 2010 Employment Inducement Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans	2
Equity award grants authorized																			7,000,000
Shares available for future issuance																		1,100,000
Award vesting period in years							3 years	5 years												5 years
Annual grant expense period							1 year
Forfeitures recorded as a result of violating the post-termination restrictions	$ 1,000,000	$ 1,300,000	$ 3,300,000
Restricted stock units, performance period									36 months
Weighted average period over which restricted stock expense expected to be recognized									3 years					2 years 10 months 10 days
Award earning percentage												50.00%	50.00%
Number of years risk free interest rate										3 years
Term of stock options					10 years
Restricted shares granted to ARI employees, value																				7,000,000
Restricted shares granted, share										117,265	214,526			682,760	635,136	663,887				158,801
Compensation expense related to employee restricted stock awards	21,000,000	20,200,000	21,200,000
Tax benefit related to compensation costs for stock-based compensation arrangements	8,200,000	7,900,000	8,200,000
Fair value of restricted stock vested during the period														46,400,000	44,800,000	67,700,000
Unrecognized compensation cost related to restricted stock														$ 13,500,000			$ 0
Expected Shares Payment For Tax Withholding For Share Based Compensation In Next Fiscal Year		300,000
Acquisition related compensation awards vesting period	3 years			2 years		5 years