Concentrations of Credit Risk and Major Customers - Receivables (Detail) (Accounts Receivable [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Concentration Risk [Line Items]
Receivables	94,712	80,535
Zhongwei Hanky Wiye Solar Co., Ltd. [Member]
Concentration Risk [Line Items]
Receivables	38,629	28,751
Alxa League Zhiwei Photovoltaic Power Generation Co., Ltd. [Member]
Concentration Risk [Line Items]
Receivables	31,243	27,008
Xinyu Realforce Energy Co., Ltd. [Member]
Concentration Risk [Line Items]
Receivables	24,840	24,776
Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Percent of Receivables	79.00%	75.00%
Customer Concentration Risk [Member] | Zhongwei Hanky Wiye Solar Co., Ltd. [Member]
Concentration Risk [Line Items]
Percent of Receivables	32.00%	27.00%
Customer Concentration Risk [Member] | Alxa League Zhiwei Photovoltaic Power Generation Co., Ltd. [Member]
Concentration Risk [Line Items]
Percent of Receivables	26.00%	25.00%
Customer Concentration Risk [Member] | Xinyu Realforce Energy Co., Ltd. [Member]
Concentration Risk [Line Items]
Percent of Receivables	21.00%	23.00%