Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Executive Retirement Plan Disclosure
Restricted cash, including amounts in the Rabbi Trust	$ 5,369,000	$ 5,377,000
Supplemental Executive Retirement Plan (SERP)
Supplemental Executive Retirement Plan Disclosure
Eligibility age	60 years
Number of months of salary taken as gross base for receipt of monthly payments	36 months
Vesting period of plan, when participants begin receiving payments	6 months
Restricted cash, including amounts in the Rabbi Trust	5,100,000	5,100,000
Reconciliation of beginning and ending balances of the projected benefit obligation
Projected benefit obligation at the beginning of the year	47,206,000	32,952,000
Service cost	5,406,000	4,315,000	4,255,000
Interest cost	1,584,000	1,475,000	1,356,000
Actuarial (gain) loss	(3,162,000)	8,464,000
Projected benefit obligation at the end of the year	51,034,000	47,206,000	32,952,000
Unfunded at end of the year	51,034,000	47,206,000
Accumulated benefit obligation	37,200,000	33,200,000
Future estimated benefit payments
2015	23,502,000
2019-2023	29,330,000
Total future estimated benefit payments	$ 52,832,000