Financial Instruments and Fair Value Disclosures - Assets and Liabilities Measured at Fair Value on Recurring and Nonrecurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Mar. 31, 2016
Assets:
Book Value of Assets	$ 6,378,814			$ 6,378,814	$ 6,219,242
Loss on assets	499,400	$ 2,600	$ 358,528
Fair Value Measurements, Recurring [Member]
Assets:
Short-term investments	105,659			105,659	113,843
Corporate bonds	11,438			11,438	4,999
Mortgage-backed securities	80			80	68
Total assets	117,177			117,177	118,910
Fair Value Measurements, Recurring [Member] | Level 1 [Member]
Assets:
Short-term investments	105,659			105,659	113,843
Total assets	105,659			105,659	113,843
Fair Value Measurements, Recurring [Member] | Level 2 [Member]
Assets:
Corporate bonds	11,438			11,438	4,999
Mortgage-backed securities	80			80	68
Total assets	11,518			11,518	5,067
Nonrecurring Fair Value Measurements [Member]
Assets:
Book Value of Assets	189,600			189,600	178,415
Loss on assets				860,441
Nonrecurring Fair Value Measurements [Member] | Level 3 [Member]
Assets:
Book Value of Assets	$ 189,600			$ 189,600	$ 178,415