Derivative Financial Instruments and Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Jan. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Notional amount										$ 1,000,000,000
Payment on termination of interest rate swaps				28,000,000
Derivative loss reclassified from accumulated other comprehensive income, before tax						28,100,000
Derivative loss reclassified from accumulated other comprehensive income, net of tax						17,300,000
Accumulated other comprehensive loss, net of tax	(54,753,000)		(97,260,000)		(54,753,000)	(97,260,000)	(55,237,000)	(57,190,000)	285,955,000		(186,584,000)
Minimum outstanding purchase commitment range					1 month
Maximum outstanding purchase commitment range					1 year
Reclassification to income statement related to de-designation of cash flow hedges	0	(220,000)	(415,783,000)		(220,000)	(415,783,000)
2017 Swaps Novated To White Wave
Derivatives, Fair Value [Line Items]
Noncontrolling interest (percent)											13.30%
Accumulated other comprehensive loss, before tax									63,400,000
Accumulated other comprehensive loss, net of tax									$ 38,900,000