Note 11 - Revolving Credit Facility and Letter of Credit Facilities (Details) (USD $)	Mar. 31, 2014
Note 11 - Revolving Credit Facility and Letter of Credit Facilities (Details) [Line Items]
Cash Collateral Deposits	$ 26,100,000
Four Committed Letter Of Credit [Member] | Letter of Credit [Member]
Note 11 - Revolving Credit Facility and Letter of Credit Facilities (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	41,000,000
Letters of Credit Outstanding, Amount	12,600,000
Unsecured Revolving Credit Facility [Member]
Note 11 - Revolving Credit Facility and Letter of Credit Facilities (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	440,000,000
Line of Credit Facility, Current Borrowing Capacity	440,000,000
Line of Credit Facility, Amount Outstanding	0
Uncommitted Letter of Credit [Member]
Note 11 - Revolving Credit Facility and Letter of Credit Facilities (Details) [Line Items]
Line of Credit Facility, Amount Outstanding	$ 13,100,000