Share-Based Compensation - Nonvested share activity and related fair value (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Nonvested Stock Shares, Weighted Average Grant Date Fair Value
Compensation expense	$ 46,613	$ 51,565	$ 57,716
Nonvested stock awards
Nonvested Stock Shares
Nonvested at the beginning of the period (in shares)	4,093,760
Granted (in shares)	1,433,673
Vested (in shares)	(1,672,676)
Forfeited (in shares)	(212,772)
Nonvested at the end of the period (in shares)	3,641,985	4,093,760
Nonvested Stock Shares, Weighted Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$ 22.79
Granted (in dollars per share)	17.65
Vested (in dollars per share)	25.52
Forfeited (in dollars per share)	21.27
Nonvested at the end of the period (in dollars per share)	$ 19.60	$ 22.79
Compensation expense	$ 46,600	$ 51,600	57,700
Related income tax benefit recognized		11,900	13,600
Remaining unamortized expense of nonvested stock expected to be recognized	$ 46,500
Period for expense amortized	2 years 1 month 6 days
Total fair value of shares vested	$ 29,100	$ 41,000	$ 20,800
Cash Settled RSU Plan
Nonvested Stock Shares
Nonvested at the beginning of the period (in shares)	1,762,060
Granted (in shares)	1,228,904
Vested (in shares)	(497,092)
Forfeited (in shares)	(118,272)
Nonvested at the end of the period (in shares)	2,375,600	1,762,060