Subsequent Events - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified		6 Months Ended	0 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 2014 Forecast [Member]	Jul. 28, 2014 Subsequent Event [Member]	Jul. 07, 2014 Subsequent Event [Member]	Jul. 28, 2014 Subsequent Event [Member] Currently Reported [Member]
Subsequent Event [Line Items]
Principal amount of its outstanding 2010 Notes for cash				$ 17.4
Non-operating loss on repurchase transaction		0.8
Interest expense expected to decrease		0.4
Diluted share expected to decrease		380,000
Unsecured credit facility	$ 275		$ 400		$ 275
Unsecured credit facility expiration date			2019-07