Employee Benefit Plans (Details)	12 Months Ended			192 Months Ended	204 Months Ended
	Dec. 31, 2016 USD ($) mo	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) yr age	Dec. 31, 2016 USD ($)
Employee Benefit Plans [Abstract]
Eligibility Period For 401K Savings Plan In Months | mo	3
Employer Matching Contribution, Percent of Match					200.00%
Employer Matching Contribution, Percent of Employees' Gross Pay					3.00%
Maximum Eligible Earnings As Established By IRS For Matching Contributions	$ 265,000	$ 265,000	$ 260,000
Employer Contribution Amount	4,000,000	3,700,000	3,500,000
Years Of Service For Supplemental Retirement Contribution | yr				10
Age Of Employee For Supplemental Retirement Contribution | age				40
Annual Supplemental Retirement Contribution And Credit Total.	21,000	42,000	$ 52,000
Separate Unrestricted Cash For Deferred Compensation Plan.	23,800,000	20,400,000		$ 23,800,000	$ 23,800,000
Deferred Compensation Liability	$ 23,800,000	$ 20,400,000		$ 23,800,000	$ 23,800,000