Share-Based Compensation (Narrative) (Detail) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended	6 Months Ended																	12 Months Ended	6 Months Ended		12 Months Ended		6 Months Ended	1 Months Ended		6 Months Ended				1 Months Ended
	Dec. 08, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 D Y	Dec. 31, 2011 Y	Jun. 30, 2012	Dec. 31, 2012 Restricted Stock [Member]	Dec. 31, 2012 Restricted Stock Units With Earning Per Share Performance Conditions [Member]	Dec. 31, 2011 Restricted Stock Units With Earning Per Share Performance Conditions [Member]	Dec. 31, 2012 Restricted Stock Units With Return On Invested Capital Performance Conditions [Member]	Dec. 31, 2012 Restricted Stock Units With Market Conditions [Member]	Dec. 31, 2011 Restricted Stock Units With Market Conditions [Member]	Dec. 31, 2012 Monte Carlo Simulation [Member]	Dec. 31, 2011 Monte Carlo Simulation [Member]	Dec. 31, 2012 2002 Plan [Member]	Dec. 31, 2011 2002 Plan [Member]	Dec. 31, 2010 2002 Plan [Member] Restricted Stock Units With Earning Per Share Performance Conditions [Member] Y	Dec. 31, 2010 2002 Plan [Member] Restricted Stock Units With Market Conditions [Member] Y	Dec. 31, 2010 2002 Plan [Member] Monte Carlo Simulation [Member]	Dec. 31, 2012 2002 Plan [Member] Restricted Stock Units [Member] Y	Dec. 31, 2011 2002 Plan [Member] Restricted Stock Units [Member] Y	Dec. 31, 2012 2002 Plan [Member] Restricted Stock Units With Performance Conditions [Member]	Dec. 31, 2011 2002 Plan [Member] Restricted Stock Units With Performance Conditions [Member]	Jun. 30, 2010 2002 Plan [Member] Restricted Stock Units With Performance Conditions [Member] Y	Dec. 31, 2012 2002 Plan [Member] Common Stock [Member]	Dec. 31, 2012 2012 Plan [Member]	Jun. 30, 2012 2012 Plan [Member]	Dec. 07, 2011 2012 Plan [Member]	Dec. 31, 2012 2012 Plan [Member] Full Value Grant [Member]	Dec. 31, 2012 2012 Plan [Member] Restricted Stock Units [Member]	Jun. 30, 2012 2012 Plan [Member] Restricted Stock Units [Member]	Dec. 31, 2012 2012 Plan [Member] Common Stock [Member]	Dec. 31, 2012 2012 Plan [Member] Stock-Settled Restricted Stock Units [Member]	Dec. 31, 2012 2012 Plan [Member] Cash-Settled Restricted Stock Units [Member]	Dec. 31, 2012 2012 Plan [Member] Stock Appreciation Rights [Member]	Sep. 30, 2008 Outside 2002 Plan [Member] Restricted Stock Units [Member]	Jan. 31, 2008 Outside 2002 Plan [Member] Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant																										3,224,134		4,400,000
Number of stock options, common stock and restricted stock units granted				486,784																0					0							486,784	549,864	869
Stock option and incentive plan, maturity date																										Dec. 07, 2021
Number of awards for reduction of shares available for grant under 2012 Plan																										1
Reduction in shares available for grant for one award under the plan																													1.71
Stock appreciation rights																																			6,803
Number of shares available for grant of stock options, stock appreciation rights, restricted stock and restricted stock units	1,100,000
Grant of stock options stock appreciation rights, restricted stock and restricted stock units not to exceed for shares of common stock	7,860,000
Share-based compensation		$ 5,400,000	$ 5,400,000	$ 10,227,000	$ 7,921,000
Total income tax benefit recognized		1,200,000	1,500,000	2,600,000	2,200,000
Weighted-average grant-date fair value of options granted		$ 15.54	$ 14.12	$ 15.92	$ 13.26
Total intrinsic value of options exercised		400,000	700,000	6,000,000	900,000
Extended vesting period after employee termination, days				90
Total unrecognized compensation cost		35,000,000		35,000,000			0
Weighted average recognition period, years				1 year 8 months 12 days			0 years
Shares, Outstanding							0
Restricted stock units granted								97,733.0	118,546	97,733	97,733	118,546					191,721	191,715	5,200,000	234,825	273,931	21,840	24,400	380,400						869	1,150					28,344	34,608
Cliff vesting period, in years				3	3
Compensation expenses recognized period (years)															3 years	3 years
Restricted stock units, grant date fair value													3,700,000	3,300,000
Cliff vesting period, in years																	3	3		3	3			3
Restricted stock units vested percentage																								39.80%
Number of restricted stock units settled				1,608	1,608																					0
Cash-settled restricted stock units, outstanding				0		1,608																				2,019	1,150
Restricted stock units settled cost				100,000	100,000
Aggregate intrinsic value of equity classified restricted stock		$ 78,600,000		$ 78,600,000