Commitments and Contingencies Narrative (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 23, 2015
Line of Credit Facility, Maximum Borrowing Capacity					$ 500,000
Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	[1]	$ 500,000		$ 500,000
Standby Letters of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 250,000	$ 300,000

[1] Refer to Note 6 for details regarding our secured credit facilities.