Financial instruments - aggregate accounts receivable, net of allowance for doubtful accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Derivatives Fair Value [Line Items]
Accounts receivable, net	$ 273,704		$ 295,290
Spain, Italy, Portugal, and Greece
Derivatives Fair Value [Line Items]
Accounts receivable, net	$ 76,190	[1]	$ 97,852	[1]
Percentage of total net current and long-term accounts receivables	27.30%		31.00%

[1] The long-term portion of accounts receivable, net from customers in Spain, Italy, Greece and Portugal at December 31, 2014 and 2013 was $11.3 million and $17.6 million, respectively, and is reported in other assets.