Employee Benefit Plans (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Expense related to benefit plans	$ 11,400,000	$ 9,200,000	$ 11,800,000
Net actuarial gain (loss) expected to be recognized	2,700,000
Modeling process confidence ratio	90.00%
Percentage of equity investments in mutual fund	69.00%
Assumed long-term rate of return	7.75%
Expected defined benefit plans contribution within a year	1,000,000
Target percentage of pay at age 55	45.00%
Target percentage of pay at age 60	60.00%
Contribution match by employer	100.00%
Participants contribution eligible for match	6.00%
Stock purchase plan expense	8,814,000	9,663,000	10,834,000
Maximum exercise period of options granted, years	10 years
Awards other than in the form of stock options	319,533
Intrinsic value of outstanding in-the-money stock options	93,400,000
Outstanding in-the-money exercisable stock options	68,000,000
Weighted-average period, unrecognized expense related to stock options, years	2 years 9 months 18 days
Weighted-average period, unrecognized expense related to non-vested stock awards, years	2 years 6 months
Weighted-average fair value of stock options granted	$ 13.74	$ 11.07	$ 9.78
401(k) Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Stock purchase plan expense	$ 11,500,000	$ 10,800,000	$ 10,200,000
Equity Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Target asset allocation percentage	62.00%
Fixed Income Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Target asset allocation percentage	35.00%
2005 Plan [Member] | Stock Options [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Life period of options awarded, years	10 years	10 years	10 years
Vesting period of options awarded, years	4 years	4 years	4 years
2005 Plan [Member] | Non Vested Stock Awards and Stock Units [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Life period of options awarded, years	10 years	10 years	10 years
Cliff vesting period, years	4 years	4 years	4 years
2007 Directors Plan [Member] | Stock Options [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Options awarded during period	0	0	0
Minimum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contribution percentage of eligible compensation	2.00%
Maximum [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contribution percentage of eligible compensation	50.00%