Treasury Stock Acquisition (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Schedule of Treasury Stock [Line Items]
Treasury stock acquired, Shares, Beginning balance	42,268,057
Treasury stock acquired, Shares, Ending balance	42,818,585
Treasury stock acquired, Values, Beginning balance	$ 880,888
Treasury stock acquired, Values	18,147
Treasury stock acquired, Values, Ending balance	899,035
2013 Program
Schedule of Treasury Stock [Line Items]
Treasury stock acquired, Shares	13,898
Treasury stock acquired, Values	466
Long Term Incentive Plan
Schedule of Treasury Stock [Line Items]
Treasury stock acquired, Shares	536,630
Treasury stock acquired, Values	$ 17,681