Employee Benefit Plans	12 Months Ended
Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	8. Employee Benefit Plans Defined-Contribution Plan The Company sponsors a qualified defined-contribution 401(k) plan that covers substantially all of its employees. Under the terms of the 401(k) plan, the Company matches a certain portion of employee contributions to their individual 401(k) accounts using the “safe harbor” guidelines provided in the Internal Revenue Code. Expenses related to matching employee contributions to the 401(k) plan were $3.7 million, $3.3 million, and $3.2 million in 2016, 2015, and 2014, respectively. Additionally, in 2016, 2015, and 2014 the Company provided discretionary supplemental contributions to the individual 401(k) accounts of substantially all employees. Each employee received a supplemental contribution to their account based on a uniform percentage of qualifying compensation established annually. The cost of these supplemental contributions totaled $6.0 million, $5.0 million, and $5.6 million in 2016, 2015, and 2014, respectively. Defined-Benefit Plans The Company previously sponsored two qualified defined-benefit pension plans that covered substantially all employees. In 2007, the Company amended its defined-benefit pension plans so that employees no longer accrued benefits under them. This action “froze” the benefits for all employees and prevented future hires from joining the plans. In December 2014 the Company terminated its defined benefit pension plans and settled all obligations to employees. As a result of the termination of the plans, the Company recognized an expense of $41.0 million in the fourth quarter of 2014, primarily comprised of the recognition of previously deferred actuarial losses. Active employees, all of whom were 100 percent vested in their pension benefits, were given the option of rolling the actuarially determined present value of their benefits into their 401(k) accounts, receiving deferred annuity contracts issued by an insurance carrier, or receiving a lump sum payment. The Company contributed $7.5 million to the frozen pension plans in 2014 in order to fully fund the settlement, representing the shortfall of the existing pension fund assets on the termination date to the settlement value. Since the plans have been fully funded and settled, no cash contributions were required in 2015 or 2016, nor will any be required in future years. In conjunction with the termination and settlement of the defined-benefit pension plans, the additional minimum pension liability was fully recognized in 2014. The Company recorded an adjustment to the additional minimum pension liability, net of tax, which increased comprehensive income by $19.4 million in 2014.

Employee Benefit Plans

12 Months Ended

Dec. 31, 2016

Compensation and Retirement Disclosure [Abstract]

8. Employee Benefit Plans

Defined-Contribution Plan

The Company sponsors a qualified defined-contribution 401(k) plan that covers substantially all of its employees. Under the terms of the 401(k) plan, the Company matches a certain portion of employee contributions to their individual 401(k) accounts using the “safe harbor” guidelines provided in the Internal Revenue Code. Expenses related to matching employee contributions to the 401(k) plan were $3.7 million, $3.3 million, and $3.2 million in 2016, 2015, and 2014, respectively.

Additionally, in 2016, 2015, and 2014 the Company provided discretionary supplemental contributions to the individual 401(k) accounts of substantially all employees. Each employee received a supplemental contribution to their account based on a uniform percentage of qualifying compensation established annually. The cost of these supplemental contributions totaled $6.0 million, $5.0 million, and $5.6 million in 2016, 2015, and 2014, respectively.

Defined-Benefit Plans

The Company previously sponsored two qualified defined-benefit pension plans that covered substantially all employees. In 2007, the Company amended its defined-benefit pension plans so that employees no longer accrued benefits under them. This action “froze” the benefits for all employees and prevented future hires from joining the plans.

In December 2014 the Company terminated its defined benefit pension plans and settled all obligations to employees. As a result of the termination of the plans, the Company recognized an expense of $41.0 million in the fourth quarter of 2014, primarily comprised of the recognition of previously deferred actuarial losses.

Active employees, all of whom were 100 percent vested in their pension benefits, were given the option of rolling the actuarially determined present value of their benefits into their 401(k) accounts, receiving deferred annuity contracts issued by an insurance carrier, or receiving a lump sum payment.

The Company contributed $7.5 million to the frozen pension plans in 2014 in order to fully fund the settlement, representing the shortfall of the existing pension fund assets on the termination date to the settlement value. Since the plans have been fully funded and settled, no cash contributions were required in 2015 or 2016, nor will any be required in future years.

In conjunction with the termination and settlement of the defined-benefit pension plans, the additional minimum pension liability was fully recognized in 2014. The Company recorded an adjustment to the additional minimum pension liability, net of tax, which increased comprehensive income by $19.4 million in 2014.