Equity Incentive Plans

12 Months Ended

Dec. 31, 2011

Share-based Compensation [Abstract]

Equity Incentive Plans

Equity Incentive Plan

All grants of common shares and options to purchase common shares were issued under the 1997 Share Incentive Plan prior to May 9, 2007, and under the 2007 Equity Incentive Plan on and after May 9, 2007. Under the 2007 Equity Incentive Plan, an aggregate of 1,950,000 common shares, options to purchase common shares and restricted share units, subject to adjustment in the event of certain capital events, may be granted. At December 31, 2011, there were 675,941 shares available for grant under the 2007 Equity Incentive Plan.

Share Options

Share options granted under both the 1997 Share Incentive Plan and the 2007 Equity Incentive Plan have exercise prices equal to the fair market value of a common share at the date of grant. The options may be granted for any reasonable term, not to exceed 10 years, and for employees typically become exercisable at a rate of 25% per year over a four-year period, however, this was typically at a rate of 20% per year over a five-year period for options granted prior to 2009. For non-employee Trustees, share options are vested upon issuance, however, the share options may not be exercised for a one year period subsequent to the grant date. The Company generally issues new common shares upon option exercise. A summary of the Company’s share option activity and related information is as follows:

	Number of shares		Option price per share					Weighted avg. exercise price
Outstanding at December 31, 2008	911,117		$	14.00	—	$	65.50	$	34.07
Exercised	(100,928	)	14.13		—	14.13		14.13
Granted	422,093		18.18		—	19.41		18.36
Forfeited	(23,994	)	18.18		—	60.03		32.73
Outstanding at December 31, 2009	1,208,288		$	14.00	—	$	65.50	$	30.27
Exercised	(168,743	)	14.00		—	42.46		20.91
Granted	39,438		36.56		—	44.98		38.23
Forfeited	(7,887	)	18.18			60.03		34.70
Outstanding at December 31, 2010	1,071,096		$	16.05	—	$	65.50	$	32.00
Exercised	(135,196	)	18.18		—	42.46		21.96
Granted	70,266		45.73		—	47.77		46.19
Forfeited	(3,333	)	16.05		—	16.05		16.05
Outstanding at December 31, 2011	1,002,833		$	18.18	—	$	65.50	$	34.41

The weighted average fair value of options granted was $9.29, $7.27 and $2.68 during 2011, 2010 and 2009, respectively. The intrinsic value of stock options exercised was $2.9 million, $3.5 million, and $1.9 million during the years ended December 31, 2011, 2010 and 2009, respectively.

At December 31, 2011, stock-option expense to be recognized in future periods was $0.9 million as follows (in thousands):

	Amount
Year:
2012	$	542
2013	221
2014	151
Total	$	914

The following table summarizes outstanding options at December 31, 2011:

Exercise price range	Options outstanding	Weighted avg. life remaining	Weighted avg. exercise price		Aggregate intrinsic value  (in thousands)
$ 18.18 - 19.99	310,807	7.1
20.00 - 29.99	172,304	1.2
30.00 - 39.99	96,303	4.1
40.00 - 49.99	310,066	5.7
50.00 - 59.99	10,000	6.4
60.00 - 65.50	103,353	5.0
	1,002,833	5.1	$	34.41	$	11,992

The following table summarizes exercisable options at December 31, 2011:

Exercise price range	Options outstanding	Weighted avg. life  remaining	Weighted avg. exercise price		Aggregate  intrinsic value (in thousands)
$ 18.18 - 19.99	110,679	7.1
20.00 - 29.99	172,304	1.2
30.00 - 39.99	72,189	2.8
40.00 - 49.99	209,978	4.5
50.00 - 59.99	10,000	6.4
60.00 - 65.50	84,686	5.1
	659,836	4.0	$	36.51	$	6,746

Nonvested Shares

A summary of the Company’s nonvested share activity and related information is as follows:

	Number  of shares		Weighted avg. grant  date fair value		Weighted avg. life remaining
Outstanding at December 31, 2010	372,308		$	33.89
Granted	137,020		45.85
Vested	(158,465	)	34.90
Outstanding at December 31, 2011	350,863		$	38.11	0.77

The holders of nonvested shares have voting rights and receive dividends from the date of grant. These shares vest ratably over a period of three to five years. The fair value of the nonvested shares that vested was $7.3 million, $5.0 million and $2.8 million for the years ended December 31, 2011, 2010 and 2009, respectively. At December 31, 2011, unamortized share-based compensation expense related to nonvested shares was $5.5 million and will be recognized in future periods as follows (in thousands):

	Amount
Year:
2012	$	2,956
2013	1,714
2014	836
Total	$	5,506

Restricted Share Units

A summary of the Company’s restricted share unit activity and related information is as follows:

	Number  of Shares		Weighted Average Grant Date Fair Value		Weighted Average Life Remaining
Outstanding at December 31, 2010	10,506		$	44.98
Granted	10,519		47.77
Vested	(10,506	)	44.98
Outstanding at December 31, 2011	10,519		$	47.77	0.36

The holders of restricted share units have voting rights and receive dividends from the date of grant. The share units vest upon the earlier of the day preceding the next annual meeting of shareholders or a change of control. The settlement date for the shares is selected by the non-employee trustee, and ranges from one year from the grant date to upon termination of service. At December 31, 2011, unamortized share-based compensation expense related to restricted share units was $167 thousand which will be recognized in 2012.