13. STOCK-BASED INCENTIVE PLANS

We are externally managed by our Manager and do not currently have any employees. However, as of September 30, 2018, our Manager, certain individuals employed by an affiliate of our Manager, and certain members of our board of directors were compensated, in part, through the issuance of stock-based instruments.

We had stock-based incentive awards outstanding or available to be awarded under nine benefit plans as of September 30, 2018: (i) our amended and restated 1997 non-employee director stock plan, or 1997 Plan; (ii) our 2007 long-term incentive plan, or 2007 Plan; (iii) our 2011 long-term incentive plan, or 2011 Plan; (iv) our 2013 stock incentive plan, or 2013 Plan; (v) our 2013 manager incentive plan, or 2013 Manager Plan; (vi) our 2016 stock incentive plan, or 2016 Plan; (vii) our 2016 manager incentive plan, or 2016 Manager Plan; (viii) our 2018 stock incentive plan, or 2018 Plan; and (ix) our 2018 manager incentive plan, or 2018 Manager Plan. We refer to our 1997 Plan, our 2007 Plan, our 2011 Plan, our 2013 Plan, our 2013 Manager Plan, our 2016 Plan, and our 2016 Manager Plan, collectively, as our Expired Plans and we refer to our 2018 Plan and 2018 Manager Plan, collectively, as our Current Plans.

Our Expired Plans have expired and no new awards may be issued under them. Under our Current Plans, a maximum of 5,000,000 shares of our class A common stock may be issued to our Manager, our directors and officers, and certain employees of affiliates of our Manager. As of September 30, 2018, we have not granted any shares under the Current Plans.

The following table details the movement in our outstanding shares of restricted class A common stock and the weighted-average grant date fair value per share:


	Restricted Class A Common Stock			Weighted-Average Grant Date Fair Value Per Share
Balance as of December 31, 2017		1,484,175		$	30.61
Granted		318,741			31.83
Vested		(404,241	)		28.89
Forfeited		(17,820	)		30.44

Balance as of September 30, 2018		1,380,855		$	31.40

These shares generally vest in installments over a three-year period, pursuant to the terms of the respective award agreements and the terms of the Current Plans. The 1,380,855 shares of restricted class A common stock outstanding as of September 30, 2018 will vest as follows: 448,474 shares will vest in 2018; 616,168 shares will vest in 2019; and 316,213 shares will vest in 2020. As of September 30, 2018, total unrecognized compensation cost relating to nonvested share-based compensation arrangements was $33.9 million based on the closing price of our class A common stock of $31.43 on June 29, 2018, the last trading day prior to our adoption of ASU 2018-07. This cost is expected to be recognized over a weighted average period of 1.0 years from September 30, 2018. The compensation cost of our share-based compensation arrangements for awards granted after our adoption of ASU 2018-07 will be a fixed amount determined based on the grant date fair value of shares granted. Refer to Note 2 for additional discussion on our adoption of ASU 2018-07.