Equity Incentive Award Plan (Tables)

9 Months Ended

Sep. 30, 2018

Equity Incentive Award Plan

Schedule of stock option activity

	Number of
	Shares	Weighted-
	Subject to	Average
	Option	Exercise Price
Options outstanding, December 31, 2017	67,789	$	19.12
Granted	—		—
Exercised	(12,881)		17.04
Forfeited	—		—
Expired	—		—
Options outstanding, September 30, 2018	54,908	$	19.60

Schedule of restricted awards and RSUs

	Restricted	Weighted-
	Stock	Average Fair
	Awards and	Value at Grant
	Units	Date
Unvested balance, December 31, 2017	289,843	$	70.71
Granted	153,219		96.95
Forfeited	(35,271)		83.56
Vested	(122,500)		64.39
Unvested balance, September 30, 2018	285,291	$	85.93

Schedule of unvested PSAs and their weighted-average fair value at the date of grant

				Weighted-
				Average Fair
	Performance-Based Restricted Stock Awards			Value at Grant
	Minimum	Maximum	Target	Date
Unvested balance, December 31, 2017	38,694	130,843	84,769	$	84.63
Granted	10,729	75,104	42,917		101.03
Performance adjustment (1)	33,403	—	16,702		—
Forfeited	—	—	—		—
Vested	(32,003)	(32,003)	(32,003)		61.22
Unvested balance, September 30, 2018	50,823	173,944	112,385	$	96.58

(1) Includes the annual adjustment for the number of PSAs earned based on our achievement of relative TSR measured versus the MSCI US REIT Index for the applicable performance periods.

Summary of assumptions used to value stock option awards

	Nine Months Ended September 30,
	2018		2017
Expected term (in years)	2.82		2.81
Expected volatility	24.15	%	23.33	%
Expected annual dividend(1)	—		—
Risk-free rate	2.24	%	1.60	%

(1) The fair value of the PSAs assumes reinvestment of dividends.