Non-Qualified Stock Option Transactions (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding Shares, Exercised	(1,800)	(2,100)
Exercisable Shares at Year End	7,599	8,049
Exercisable Weighted Average Exercise Price at Year-End	$ 31.79	$ 30.06
Exercisable Aggregate Intrinsic Value at Year End	$ 64,819	$ 50,365
Nonqualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding Shares, Beginning Balance	10,148
Outstanding Shares, Granted	1,346
Outstanding Shares, Exercised	(1,409)
Outstanding Shares, Cancelled	(85)
Outstanding Shares, Forfeited	(94)
Outstanding Shares, Ending Balance	9,906
Outstanding Weighted Average Exercise Price, Beginning Balance	$ 31.23
Outstanding Weighted Average Exercise Price, Granted	$ 38.62
Outstanding Weighted Average Exercise Price, Exercised	$ 24.26
Outstanding Weighted Average Exercise Price, Cancelled	$ 33.26
Outstanding Weighted Average Exercise Price, Forfeited	$ 33.97
Outstanding Weighted Average Exercise Price, Ending Balance	$ 33.18
Outstanding Aggregate Intrinsic Value, Balance at Year End	$ 69,079	$ 51,402
Exercisable Shares at Year End	7,599
Exercisable Weighted Average Exercise Price at Year-End	$ 31.79