3. Recent Accounting Pronouncements 3. Recent Accounting Pronouncements - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, unbilled and retainage	$ 70,536	$ 206,739
Deferred project costs, Current		0
Project assets - current	0	700,800
Prepaid expenses and other current assets	177,358	217,462
Total current assets	3,330,238	3,787,829
Project assets and deferred project costs		0
Project assets - noncurrent	960,089	762,148
Deferred tax assets, net	251,453	255,152
Investments in unconsolidated affiliates and joint ventures	228,469	234,610
Other assets	85,104	77,898
Total assets	6,604,503	6,824,368
Income taxes payable	5,002	12,562
Billings in excess of costs and estimated earnings		0
Payments and billings for deferred project costs		0
Deferred revenue	24,754	308,704
Other current liabilities	156,963	146,942
Total current liabilities	527,051	907,881
Other liabilities	414,752	371,439
Total liabilities	1,376,697	1,606,019
Additional paid-in capital	2,767,941	2,765,310
Accumulated earnings	2,471,971	2,462,842
Total stockholders' equity	5,227,806	5,218,349
Total liabilities and stockholders' equity	$ 6,604,503	6,824,368
Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, unbilled and retainage		205,530
Deferred project costs, Current		701,105
Project assets - current		0
Prepaid expenses and other current assets		217,157
Total current assets		3,786,620
Project assets and deferred project costs		800,770
Project assets - noncurrent		0
Deferred tax assets, net		252,655
Investments in unconsolidated affiliates and joint ventures		242,361
Other assets		78,076
Total assets		6,867,213
Income taxes payable		5,288
Billings in excess of costs and estimated earnings		115,623
Payments and billings for deferred project costs		284,440
Deferred revenue		0
Other current liabilities		54,683
Total current liabilities		899,707
Other liabilities		428,120
Total liabilities		1,654,526
Additional paid-in capital		2,759,211
Accumulated earnings		2,463,279
Total stockholders' equity		5,212,687
Total liabilities and stockholders' equity		6,867,213
Accounting Standards Update 2014-09 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, unbilled and retainage		1,209
Deferred project costs, Current		(701,105)
Project assets - current		700,800
Prepaid expenses and other current assets		305
Total current assets		1,209
Project assets and deferred project costs		(800,770)
Project assets - noncurrent		762,148
Deferred tax assets, net		2,497
Investments in unconsolidated affiliates and joint ventures		(7,751)
Other assets		(178)
Total assets		(42,845)
Income taxes payable		7,274
Billings in excess of costs and estimated earnings		(115,623)
Payments and billings for deferred project costs		(284,440)
Deferred revenue		308,704
Other current liabilities		92,259
Total current liabilities		8,174
Other liabilities		(56,681)
Total liabilities		(48,507)
Additional paid-in capital		6,099
Accumulated earnings		(437)
Total stockholders' equity		5,662
Total liabilities and stockholders' equity		$ (42,845)