Note 12 - Senior Notes Schedule of Senior Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Senior Notes	$ 1,030,348	$ 1,027,074
Senior Notes Due 2019
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.50%
Senior Notes Due 2020
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.25%
Senior Notes Due 2021
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.00%
Senior Notes Due 2024
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		4.50%
Senior Notes
Debt Instrument [Line Items]
Senior Notes	$ 1,030,348	$ 1,027,074
Senior Notes \| Senior Notes Due 2019
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.50%
Senior Notes	$ 158,324	157,636
Senior Notes \| Senior Notes Due 2020
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.25%
Senior Notes	$ 232,729	231,834
Senior Notes \| Senior Notes Due 2021
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.00%
Senior Notes	$ 195,867	195,146
Senior Notes \| Senior Notes Due 2024
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.50%
Senior Notes	$ 443,428	$ 442,458

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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