Long-Term Obligations - Senior Notes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Senior Notes 2018 [Member] | 2018 [Member]
Debt Instrument [Line Items]
Debt instrument issuance date	Oct. 05, 2010
Debt instrument face amount	$ 500,000,000
Senior Notes 2018 [Member] | Senior Notes [Member] | 2018 [Member] | Senior Notes 2018 To Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 270,800,000
Debt instrument repurchase date	Jul. 17, 2014
Redemption price percentage	105.953%
Long-term debt, fair value	$ 0	$ 0
Senior Notes 2018 [Member] | Senior Notes [Member] | 2018 [Member] | Senior Notes 2018 To Senior Notes 2022 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 500,000,000
Senior Notes 2022 [Member] | Senior Notes [Member] | 2022 [Member]
Debt Instrument [Line Items]
Debt instrument issuance date	Jul. 01, 2014
Debt instrument face amount	$ 1,000,000,000
Debt instrument redemption end date	Jul. 15, 2017
Debt instrument redemption price percentage	100.00%
Senior Notes 2022 [Member] | Senior Notes [Member] | 2022 [Member] | Senior Notes 2018 To Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Debt instrument issuance date	Jun. 17, 2014
Debt conversion original debt date	Jun. 30, 2014
Debt conversion converted instrument issuance date	Jul. 01, 2014
Prior tender premium affected on debt instrument redeemed by premium	2.00%
Debt instrument principal payment redeemed including premium	106.309%
Debt instrument accrued interest	$ 298,700,000
Senior Notes 2022 [Member] | Senior Notes [Member] | 2022 [Member] | Senior Notes 2019 To Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Debt instrument issuance date	Jun. 17, 2014
Debt conversion original debt date	Jun. 30, 2014
Debt conversion converted instrument issuance date	Jul. 01, 2014
Prior tender premium affected on debt instrument redeemed by premium	2.00%
Debt instrument principal payment redeemed including premium	106.629%
Debt instrument accrued interest	$ 215,300,000
Senior Notes 2022 [Member] | Senior Notes [Member] | 2022 [Member] | Equity Proceeds Redemption of Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Debt instrument redemption end date	Jul. 15, 2017
Debt instrument redemption price percentage	105.375%
Debt instrument redemption description	Equity Offering
Debt instrument redemption period	90 days
Debt instrument redemption percentage maximum redeemable	40.00%
Debt instrument redemption percentage minimum remaining	60.00%
Senior Notes 2019 [Member] | Senior Notes [Member] | 2019 [Member]
Debt Instrument [Line Items]
Debt instrument issuance date	Nov. 24, 2010
Debt instrument face amount	$ 650,000,000
Senior Notes 2019 [Member] | Senior Notes [Member] | 2019 [Member] | Senior Notes 2019 To Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 200,000,000
Debt instrument repurchase date	Nov. 24, 2014
Redemption price percentage	103.938%
Long-term debt, fair value	$ 0	$ 0