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
		Mar. 31, 2018	Mar. 31, 2017
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Non-cash stock-based compensation expense		$ 3,182	$ 3,773
Income Tax Effects:
Income tax effect of non-cash stock-based compensation		800	1,200
Excess tax benefit from non-cash stock-based compensation	[1]	0	0
Net income tax effect		(11,126)	(27,358)
Share-Based Compensation [Member]
Income Tax Effects:
Net income tax effect			(200)
General and Administrative Expenses [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Non-cash stock-based compensation expense		$ 3,200	$ 3,800

[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 three month period ended March 31, 2018, tax benefits, net of tax deficiencies, related to the vesting of share-based payment awards were de minimis, and, for the three month period ended March 31, 2017, the Company recognized a tax deficiency, net of tax benefits, of $0.2 million.