Note 15 - Accumulated Other Comprehensive Income ("AOCI") - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Balance at the end of the year	$ 5,425,602	$ 5,444,685
Balance at the beginning of the year	5,402,874	5,181,951
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Other comprehensive income before reclassifications	1,721	2,354
Amounts reclassified from AOCI
Net current-period other comprehensive income	1,721	2,354
Balance at the end of the year	8,056	8,970
Balance at the beginning of the year	6,335	6,616
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Other comprehensive income before reclassifications	(1,619)	(33)
Amounts reclassified from AOCI
Net current-period other comprehensive income	(1,619)	(33)
Balance at the end of the year	(1,213)	365
Balance at the beginning of the year	406	398
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Other comprehensive income before reclassifications	205	(759)
Amounts reclassified from AOCI
Net current-period other comprehensive income	205	(759)
Balance at the end of the year	(770)	(2,185)
Balance at the beginning of the year	(975)	(1,426)
AOCI Attributable to Parent [Member]
Other comprehensive income before reclassifications	307	1,562
Amounts reclassified from AOCI
Net current-period other comprehensive income	307	1,562
Balance at the end of the year	6,073	7,150
Balance at the beginning of the year	$ 5,766	$ 5,588