Employee Benefit Plans and Shareholder Rights Plan (Tables)

12 Months Ended

Dec. 31, 2017

Employee Benefit Plans and Shareholder Rights Plan [Abstract]

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following is a summary of our restricted stock and restricted stock unit activity for 2017, 2016 and 2015:

	Number		Weighted Average Fair Value		Aggregate Intrinsic Value
Balance at December 31, 2014	814,400		$	63.30
Granted	380,991		52.40
Issued	(311,119	)	57.94		$	16,518,000
Forfeited	(52,981	)	60.45
Balance at December 31, 2015	831,291		60.49
Granted	587,953		27.90
Issued	(278,572	)	61.48		$	7,866,000
Forfeited	(88,665	)	43.03
Balance at December 31, 2016	1,052,007		43.48
Granted	489,514		26.70
Issued	(277,968	)	61.90		$	7,038,000
Forfeited	(81,748	)	34.15
Balance at December 31, 2017	1,181,805		$	32.84