Equity Incentive Award Plan (Tables)

6 Months Ended

Jun. 30, 2017

Equity Incentive Award Plan

Schedule of stock option activity

	Number of
	Shares	Weighted-
	Subject to	Average
	Option	Exercise Price
Options outstanding, December 31, 2016	265,550	$	22.96
Granted	—		—
Exercised	(190,448)		24.56
Forfeited	—		—
Expired	—		—
Options outstanding, June 30, 2017	75,102	$	19.15

Schedule of unvested shares subject to options

	Number of	Weighted-
	Shares	Average Fair
	Subject to	Value at Grant
	Option	Date
Unvested balance, December 31, 2016	16,323	$	9.99
Granted	—		—
Forfeited	—		—
Vested	(16,323)		9.99
Unvested balance, June 30, 2017	—	$	—

Schedule of restricted awards and RSUs

		Weighted-
	Restricted	Average Fair
	Awards and	Value at Grant
	Units	Date
Unvested balance, December 31, 2016	323,641	$	53.84
Granted	137,260		86.24
Forfeited	(29,806)		63.84
Vested	(127,517)		42.69
Unvested balance, June 30, 2017	303,578	$	70.54

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, 2016	44,835	167,725	113,976	$	54.24
Granted	7,210	50,472	28,841		105.50
Performance adjustment (1)	62,841	—	23,725		—
Forfeited	(5,674)	(16,836)	(11,255)		79.09
Vested	(70,518)	(70,518)	(70,518)		25.89
Unvested balance, June 30, 2017	38,694	130,843	84,769	$	84.63

(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

	Six Months Ended June 30,
	2017		2016
Expected term (in years)	2.81		2.83
Expected volatility	23.33	%	25.29	%
Expected annual dividend(1)	—		—
Risk-free rate	1.60	%	0.97	%

The fair value of the PSAs assumes reinvestment of dividends.