Accounting Policies and Related Matters (Details 2) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Accounting Policies and Related Matters [Line Items]
Cash disbursed for acquisitions		$ (405,609)	$ (102,356)
Decrease (increase) in restricted cash		0	0
Net cash provided from (used in) investing activities		421,077	920,174
Increase (decrease) in cash and cash equivalents		(45,184)	(184,083)
Cash and cash equivalents at beginning of period		243,777	607,220
Cash and cash equivalents at end of period		$ 202,824	423,137
As Previously Reported
Accounting Policies and Related Matters [Line Items]
Cash disbursed for acquisitions			(102,356)
Decrease (increase) in restricted cash			145,065
Net cash provided from (used in) investing activities			1,065,239
Increase (decrease) in cash and cash equivalents	[1]		(39,018)
Cash and cash equivalents at beginning of period	[1]		419,378
Cash and cash equivalents at end of period	[1]		380,360
Accounting Standards Update 2016-18 [Member] | As Reported
Accounting Policies and Related Matters [Line Items]
Cash disbursed for acquisitions			(102,356)
Decrease (increase) in restricted cash			0
Net cash provided from (used in) investing activities			920,174
Increase (decrease) in cash and cash equivalents	[1]		(184,083)
Cash and cash equivalents at beginning of period	[1]		607,220
Cash and cash equivalents at end of period	[1]		$ 423,137

[1] Amounts in As Reported column include cash and cash equivalents and restricted cash as required. Amounts in the As Previously Reported column reflect only cash and cash equivalents.