Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Equity [Line Items]
Authorized amount for share repurchase program	$ 100
Company repurchased, shares	1.3
Repurchase of Company stock for retirement	55.7
Cash Dividend on Common Stock	$ 0.50
Aggregated Dividend Paid	26.1
Common stock Dividend Payable Date	Apr. 12, 2013
Dividend payable date of record	Mar. 28, 2013
Dividend payable date declared	Feb. 14, 2013
$925 Million Credit Facility [Member]
Equity [Line Items]
Total credit facility	$ 925.0