Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities Restricted Cash (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Cash, Cash Equivalents and Restricted Cash	$ 826,089	$ 632,921
Cash and cash equivalents inclusive of restricted cash at beginning of period	546,721	401,846	$ 515,646	$ 443,420
Cash and Cash Equivalents inclusive of Restricted Cash [Member]
Cash and cash equivalents inclusive of restricted cash at beginning of period	$ 826,089	$ 632,921	$ 781,283	$ 673,173