Share-Based Compensation - Stock Option Plans (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) item $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares
Share-based compensation disclosures
Share-based compensation expense | $	$ 31,900	$ 32,000	$ 47,300
Liability related to awards | $	130,970	116,775
Restricted Stock Award
Share-based compensation disclosures
Share-based compensation expense | $	$ 31,400	$ 31,300	37,000
Share-based compensation expense related to the closing of the Merger | $			$ 8,700
Number of types of performance share awards | item	2
Option to purchase common stock available for grant	5,700,000
Shares awarded during period	1,130,000
Options
Forfeited (in shares)	(150,000)
Weighted Average Exercise Price
Forfeited (in dollars per share) | $ / shares	$ 12.33
Restricted Stock Award | Employees and Director
Share-based compensation disclosures
Shares awarded during period	1,130,304	1,885,440	2,546,801
Aggregate value of restricted stock awards at date of grant | $	$ 14,500	$ 20,500	$ 34,800
Fair value of awards vested | $	$ 19,200	13,500	18,300
Restricted Stock Award | Maximum
Share-based compensation disclosures
Vesting period of shares	5 years
Restricted Stock Award | Maximum | Employees and Director
Share-based compensation disclosures
Vesting period of shares	4 years
Restricted Stock Based on Performance Conditions
Share-based compensation disclosures
Shares awarded during period	462,000
Fair value of awards vested | $	$ 7,100	13,900	5,900
Restricted Stock Based on Performance Conditions | Executives
Share-based compensation disclosures
Vesting period of shares	3 years
Total fair value of option vested during the period | $	$ 7,100	$ 1,500	$ 6,800
Shares awarded during period	461,919	1,284,829	438,307
Liability related to awards | $	$ 2,200	$ 2,500
Restricted Stock Based on Market Conditions
Share-based compensation disclosures
Vesting period of shares	3 years
Shares awarded during period	397,692	749,427	544,925
Aggregate value of restricted stock awards at date of grant | $	$ 4,400	$ 4,200	$ 4,700
Assumptions used to value grant date fair value
Risk free interest rate (as a percent)	1.62%	1.41%	1.18%
Expected volatility (as a percent)	55.00%	52.00%	50.00%
Closing stock price at grant date (in dollars per share) | $ / shares	$ 16.81	$ 8.64	$ 12.98
Expected term (in years)	3 years	3 years	3 years
Key Officer Director and Managerial Employee Stock Options
Share-based compensation disclosures
Option to purchase common stock available for grant	6,800,000	8,000,000
Exercise period	10 years
Total fair value of option vested during the period | $	$ 500	$ 1,900	$ 1,900
Options
Options outstanding at the beginning of the period (in shares)	5,217,000
Granted (in shares)	124,000	99,711
Exercised (in shares)	(842,000)
Forfeited (in shares)	(105,000)
Options outstanding at the end of the period (in shares)	4,394,000	5,217,000
Options exercisable at the end of the period (in shares)	4,360,000
Weighted Average Exercise Price
Options outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 12.56
Granted (in dollars per share) | $ / shares	8.59
Exercised (in dollars per share) | $ / shares	9.85
Forfeited (in dollars per share) | $ / shares	9.43
Options outstanding at the end of the period (in dollars per share) | $ / shares	13.04	$ 12.56
Options exercisable at the end of the period (in dollars per share) | $ / shares	$ 13.03
Weighted Average Remaining Contractual Term
Options outstanding at the end of the period	2 years 9 months 22 days
Options exercisable at the end of the period	2 years 9 months 7 days
Assumptions used to value grant date fair value
Granted (in dollars per share) | $ / shares	$ 2.86	$ 3.52	$ 4.40
Risk free interest rate (as a percent)	1.85%	1.09%	1.29%
Dividend yield (as a percent)	2.94%	2.21%	2.05%
Expected volatility (as a percent)	50.82%	45.69%	50.01%
Expected term (in years)	4 years	4 years	4 years
Key Officer Director and Managerial Employee Stock Options | Employees Executives And Directors
Share-based compensation disclosures
Vesting period of shares	4 years	4 years	4 years
Options
Granted (in shares)	124,271	99,711	158,219