Company's Debt Maturities on Calendar Year Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Debt Instrument [Line Items]
Total	$ 1,486,312		$ 1,394,077
2015	45,843
2016	344,572
2017	61,123
2018	505,236
2019	61,123
Thereafter	468,415
Senior Secured Notes
Debt Instrument [Line Items]
Total	758,750		774,030
2015	45,843
2016	61,123
2017	61,123
2018	61,123
2019	61,123
Thereafter	468,415
1.50% Convertible Notes
Debt Instrument [Line Items]
Total	344,113	[1]	339,943
2018	344,113	[1]
2.50% Convertible Notes
Debt Instrument [Line Items]
Total	283,449	[2]	280,104
2016	283,449	[2]
Variable Funding Notes
Debt Instrument [Line Items]
Total	100,000
2018	$ 100,000

[1] Reflects the net debt carrying amount of the 1.50% Convertible Notes in the consolidated balance sheet as of March 31, 2015, in accordance with accounting for convertible notes. The principal amount owed to the holders of the 1.50% Convertible Notes is $400.0 million.

[2] Reflects the net debt carrying amount of the 2.50% Convertible Notes in the consolidated balance sheet as of March 31, 2015, in accordance with accounting for convertible notes. The principal amount owed to the holders of the 2.50% Convertible Notes is $300.0 million.