Stock-Based Compensation and Other Employee Benefit Plans (Schedule of Non-Cash Stock-Based Compensation Expense and Related Tax Effects) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Non-cash stock-based compensation expense		$ 3,500	$ 3,400	$ 10,086	$ 10,551
Income Tax Effects:
Income tax effect of non-cash stock-based compensation		900	1,300	2,700	3,800
Excess tax benefit from non-cash stock-based compensation	[1]	100	0	300	100
Tax benefits (deficiencies), net		$ (25,091)	$ (43,378)	(71,999)	(126,170)
Stock Compensation Plan [Member]
Income Tax Effects:
Tax benefits (deficiencies), net				$ 300	$ (100)

[1] Excess tax benefits represent cash flows from tax deductions in excess of the tax effect of compensation expense associated with share-based payment arrangements. For the nine month period ended September 30, 2018, the Company recognized a tax benefit, net of tax deficiencies, related to the vesting of share-based payment awards of $0.3 million, and for the nine month period ended September 30, 2017, recognized a tax deficiency, net of tax benefits, of $0.1 million.