Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				5 Months Ended	9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	May 31, 2013	Sep. 30, 2013	Sep. 30, 2012
Equity [Line Items]
Authorized amount for share repurchase program						$ 100.0
Company repurchased, shares					2.3
Repurchase of Company stock for retirement					100.0
Cash Dividend on Common Stock	$ 0.50	$ 0.50	$ 0.50			$ 1.50
Aggregated Dividend Paid	$ 25.3	$ 25.3	$ 25.8
Common stock Dividend Payable Date	Oct. 15, 2013	Jul. 15, 2013	Apr. 12, 2013
Dividend payable date of record	Sep. 27, 2013	Jun. 28, 2013	Mar. 28, 2013
Dividend payable date declared	Sep. 13, 2013	Jun. 03, 2013	Feb. 14, 2013