Note 5 - Stock-based Compensation

3 Months Ended

Mar. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

5.	Stock-Based Compensation

We account for share-based awards in accordance with ASC Topic

718,

Compensation – Stock Compensation

("ASC

718")

which requires that the cost resulting from all share-based payment transactions be recognized in the financial statements. ASC

718

requires all entities to apply a fair value-based measurement method in accounting for share-based payment transactions with employees except for equity instruments held by employee share ownership plans.

Total compensation expense recognized related to stock-based compensation was

$4.3

million and

$3.8

million for the

three

months ended

March

31,

2017

and

2016,

respectively. As of

March

31,

2017,

total unrecognized stock-based compensation expense was

$23.4

million, with a weighted average period over which the remaining unrecognized compensation expense is expected to be recorded of approximately

1.8

years.