Note 12 - Notes Payable - Repaid Notes (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Senior Note 1 [Member]
Amount Repaid	$ 300.0	[1]
Interest Rate	6.875%	[1]
Maturity Date	Oct. 31, 2019	[1]
Senior Note 2 [Member]
Amount Repaid	$ 15.1	[2]
Interest Rate	3.20%	[2]
Maturity Date	May 31, 2021	[2]
Medium-term Notes [Member]
Amount Repaid	$ 300.0	[3]
Interest Rate	4.30%	[3]
Maturity Date	Feb. 28, 2018	[3]
Term Loan [Member]
Amount Repaid	$ 250.0
Maturity Date	Jan. 31, 2017
Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member]
Basis Spread on Variable Rate	0.95%

[1] The Company recorded an early extinguishment of debt charge of $12.8 million resulting from the early repayment of these notes.

[2] Represents partial repayments. As of December 31, 2018, these notes had an outstanding balance of $484.9 million.

[3] On August 1, 2017, the Company made a tender offer to purchase any and all of these MTN notes outstanding. As a result, the Company accepted the tender of $211.0 million of its $300.0 million outstanding MTN notes on August 10, 2017. In connection with this tender offer, the Company recorded a tender premium of $1.8 million resulting from the partial repayment of the MTN notes. In addition, in November 2017, the Company redeemed the remaining $89.0 million outstanding MTN notes.