Stock-Based Compensation (Detail) - Stock-Based Compensation Expense By Award Type (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 7,400	[1]	$ 0	[1]	$ 27,049	[1]	$ 28,021	[1]
Stock appreciation rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1,100		0		4,100		5,000
Common stock equivalents (CSEs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	100		0		400		400
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 6,200		$ 0		$ 22,500		$ 22,600

[1] Includes charges of $1.8 million and $1.5 million for the three months ended September 30, 2013 and 2012, respectively, for awards to retirement-eligible employees since these awards vest on an accelerated basis. The nine months ended September 30, 2013 and 2012 include retirement-eligible charges of $10.6 million and $4.7 million, respectively.