Defined Contribution Benefit Plans	12 Months Ended
Dec. 31, 2018
Retirement Benefits [Abstract]
Defined Contribution Benefit Plans	DEFINED CONTRIBUTION BENEFIT PLANS ESA Management has a savings plan that qualifies under Section 401(k) of the Code for all employees meeting the eligibility requirements of the plan. Through December 31, 2015, the plan had an employer-matching contribution of 50% of the first 6% of an employee’s contribution, which vested over an employee’s initial five-year service period. For the period from January 1, 2016 through September 9, 2016, the plan had an employer-matching contribution of 100% of the first 3% of an employee’s contribution and 50% of the next 2% of an employee’s contribution, which vested immediately. Beginning January 1, 2017, the plan has an employer-matching contribution of 50% of the first 6% of an employee’s contribution, which vests over an employee’s initial three-year service period. The plan also provides for contribution of up to 100% of eligible employee pretax salary, subject to the Code’s annual deferral limit of $18,500 during 2018 and $18,000 during 2017 and 2016. Employer contributions, net of forfeitures, totaled $1.8 million, $1.7 million and $2.7 million for the years ended December 31, 2018, 2017 and 2016, respectively. In June 2016, ESA Management established a non-qualified deferred compensation plan to allow certain eligible employees an option to defer a portion of their compensation on a tax-deferred basis. Beginning January 2017, the plan had an employer-matching contribution of 50% of the first 6% of an employee’s contribution, which vests over a three-year service period. The plan is fully funded in a Rabbi Trust, which is subject to creditor claims in the event of insolvency, but the assets held in the Rabbi Trust are not available for general corporate purposes. As of December 31, 2018 and 2017, plan assets and liabilities of $1.4 million and $0.9 million, respectively, are included in other assets and accounts payable and accrued liabilities on the accompanying consolidated balance sheets.

DEFINED CONTRIBUTION BENEFIT PLANS

ESA Management has a savings plan that qualifies under Section 401(k) of the Code for all employees meeting the eligibility requirements of the plan. Through December 31, 2015, the plan had an employer-matching contribution of 50% of the first 6% of an employee’s contribution, which vested over an employee’s initial five-year service period. For the period from January 1, 2016 through September 9, 2016, the plan had an employer-matching contribution of 100% of the first 3% of an employee’s contribution and 50% of the next 2% of an employee’s contribution, which vested immediately. Beginning January 1, 2017, the plan has an employer-matching contribution of 50% of the first 6% of an employee’s contribution, which vests over an employee’s initial three-year service period. The plan also provides for contribution of up to 100% of eligible employee pretax salary, subject to the Code’s annual deferral limit of $18,500 during 2018 and $18,000 during 2017 and 2016. Employer contributions, net of forfeitures, totaled $1.8 million, $1.7 million and $2.7 million for the years ended December 31, 2018, 2017 and 2016, respectively.

In June 2016, ESA Management established a non-qualified deferred compensation plan to allow certain eligible employees an option to defer a portion of their compensation on a tax-deferred basis. Beginning January 2017, the plan had an employer-matching contribution of 50% of the first 6% of an employee’s contribution, which vests over a three-year service period. The plan is fully funded in a Rabbi Trust, which is subject to creditor claims in the event of insolvency, but the assets held in the Rabbi Trust are not available for general corporate purposes. As of December 31, 2018 and 2017, plan assets and liabilities of $1.4 million and $0.9 million, respectively, are included in other assets and accounts payable and accrued liabilities on the accompanying consolidated balance sheets.