Note 5 - Variable Interest Entities (Details) - Assets and Liabilities For the Company's VIEs (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Mar. 31, 2013	Dec. 31, 2012		Dec. 31, 2011
Assets:
Restricted cash and cash equivalents	$ 51,065
Property, plant and equipment, net	1,452,336		1,233,525	1,252,873
Construction-in-process	288,827			396,141
Total assets	2,159,433	[1]	2,133,925	2,087,523	[1]	2,314,718	[1]
Liabilities:
Accounts payable and accrued expenses	98,047			98,001
Billings in excess of costs and estimated earnings on uncompleted contracts	7,903			25,408
Long-term debt	965,840
Other long-term liabilities	3,529
Total liabilities	1,414,322
Wholly Owned Subsidiaries with Project Debt [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets:
Restricted cash and cash equivalents	48,276			76,537
Other current assets	66,671			73,135
Property, plant and equipment, net	1,190,467			992,548
Construction-in-process	136,486			248,890
Other long-term assets	56,601			57,337
Total assets	1,498,501			1,448,447
Liabilities:
Accounts payable and accrued expenses	16,087			25,477
Billings in excess of costs and estimated earnings on uncompleted contracts				1,718
Long-term debt	632,906			595,425
Other long-term liabilities	103,538			81,070
Total liabilities	752,531			703,690
Wholly Owned Subsidiaries with PPAs [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets:
Other current assets	5,459			8,766
Property, plant and equipment, net	190,616			196,173
Construction-in-process	461			4,885
Other long-term assets	267			273
Total assets	196,803			210,097
Liabilities:
Accounts payable and accrued expenses	2,608			5,393
Other long-term liabilities	5,948			8,386
Total liabilities	8,556			13,779
Less Than Majority-Owned Subsidiaries [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets:
Construction-in-process	11,055			11,121
Total assets	$ 11,055			$ 11,121

[1] Including unconsolidated investments