Stock-Based Compensation - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified				12 Months Ended								12 Months Ended				12 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Deferred Compensation Plan [Member]	Dec. 31, 2013 Stock Appreciation Rights (SARs) [Member]	Dec. 31, 2013 Restricted Shares [Member] Restricted Stock Units [Member]	Dec. 31, 2013 Restricted Shares [Member] Restricted Stock Units [Member] Minimum [Member]	Dec. 31, 2013 Restricted Shares [Member] Restricted Stock Units [Member] Maximum [Member]	Dec. 31, 2013 May 17, 2012 Nonvested Common Stock Share Awards under 2004 Non-Employee Director Fee Plan [Member]	Dec. 31, 2013 Nonvested Common Stock Share Awards under 2004 Non-Employee Director Fee Plan [Member]	May 20, 2011 Nonvested Common Stock Share Awards under 2004 Non-Employee Director Fee Plan [Member]	Dec. 31, 2013 May 20, 2011 Nonvested Common Stock Share Awards under 2004 Non-Employee Director Fee Plan [Member]	Dec. 31, 2013 Nonvested Common Stock Share Awards [Member]	Dec. 31, 2013 Deferred Compensation Plan [Member]	Dec. 31, 2012 Deferred Compensation Plan [Member]	Dec. 31, 2013 Deferred Compensation Plan [Member] President, Executive Vice Presidents and Senior Vice Presidents [Member]	Dec. 31, 2013 Deferred Compensation Plan [Member] Vice President [Member]	Dec. 31, 2013 2011 Equity Incentive Plan [Member]	Dec. 31, 2013 2001 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized stock-based compensation costs	$ 0	$ 0	$ 0
Number of shares of common stock available under the 2011 plan																		4.0
2001 Equity Incentive Plan																			Mar. 14, 2011
Share-based compensation plan expiration					10 years
Share-based compensation vesting period					One-third on each of the first three anniversaries of the date of grant	One-third on each of the first three anniversaries of the date of grant
Weighted average period				2 years 9 months 18 days	1 year 4 months 24 days	1 year 4 months 24 days							2 months 12 days
Total unrecognized compensation cost				100,000	2,100,000	19,000,000							100,000
Range of vesting possibilities							0.00%	100.00%
Value of initial granted shares of common stock to new non employee director										60,000
Vesting period of initial granted shares of common stock to new non employee director										Twelve equal quarterly installments, one-twelfth on the date of grant and an additional one-twelfth on each successive third monthly anniversary of the date of grant
Value of Annual Retainer to New Non-Employee Director									125,000			95,000
Annual Retainer payable in cash to New Non Employee Director									50,000			50,000
Amended vesting period of cash Annual retainer to non-employee chairman and committee members										Vests in four equal quarterly installments, one-fourth on the day following the annual meeting of shareholders, and an additional one-fourth on each successive third monthly anniversary of the date of grant
Vesting period of annual granted shares of common stock to non-employee director										Vests in eight equal quarterly installments, one-eighth on the day following the annual meeting of shareholders, and an additional one-eighth on each successive third monthly anniversary of the date of grant
Increased stock component of annual retainer									30,000
Vesting period for the annual equity award									1 year			2 years
Amended vesting period of annual granted shares of common stock to non-employee director										Four equal quarterly installments, one-fourth on the date of grant and an additional one-fourth on each successive third monthly anniversary of the date of grant
Value Payable in Stock									75,000			45,000
Additional annual cash award to be given to any non employee chairman of board											100,000
Additional annual cash award to be given to Chairperson of the audit committee											20,000
Additional annual cash award to be given to audit committee members											10,000
Annual cash awards for the Chairpersons of the Compensation and Human Resource Development Committee, Finance Committee and Nominating and Corporate Governance Committee											12,500
Annual cash awards for the members of the Compensation and Human Resource Development Committee, Finance Committee and Nominating and Corporate Governance Committee											7,500
Increased additional annual cash award to Chairperson of Compensation and Human Resource Development Committee											15,000
Percentage of contribution in respect of amounts deferred by certain senior management participants														50.00%
Amounts deferred by certain senior management personnel																12,000	7,500
Vesting period of matching contributions and associated earnings														Over a seven year service period
Accrued employee compensation and benefits														6,400,000	5,300,000
Common stock match associated with the deferred compensation plan carrying value														$ 1,600,000	$ 1,400,000