Note 6 - Fair Value Measurements (Details) - Estimated Fair Value of Senior Notes (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Mar. 31, 2014 5.375% Senior Notes Due December 2014 [Member]	Dec. 31, 2013 5.375% Senior Notes Due December 2014 [Member]	Jun. 30, 2014 5.375% Senior Notes Due July 2015 [Member]	Dec. 31, 2013 5.375% Senior Notes Due July 2015 [Member]	Jun. 30, 2014 5.625% Senior Notes Due 2020 [Member]	Dec. 31, 2013 5.625% Senior Notes Due 2020 [Member]	Jun. 30, 2014 5.5% Senior Notes Due 2024 [Member]	Jun. 30, 2014 6.000% Senior Notes Due January 2043 [Member]	Dec. 31, 2013 6.000% Senior Notes Due January 2043 [Member]
Note 6 - Fair Value Measurements (Details) - Estimated Fair Value of Senior Notes [Line Items]
Carrying Amount	$ 1,096,112	$ 1,095,620	$ 249,700	$ 249,814	$ 249,956	$ 249,935	$ 246,156	$ 245,871	$ 250,000	$ 350,000	$ 350,000
Fair Value	$ 1,118,651	$ 1,086,083		$ 258,750	$ 259,850	$ 262,562	$ 270,938	$ 259,688	$ 258,250	$ 329,613	$ 305,083