Related Party Transactions	12 Months Ended
Dec. 31, 2013
Related Party Transactions [Abstract]
Related Party Transactions	10. Related Party Transactions Avista Utica Joint Venture. Effective September 2011, the Company’s wholly-owned subsidiary, Carrizo (Utica) LLC, entered into a joint venture in the Utica Shale with ACP II Marcellus LLC (“ACP II”), which is also one of our joint venture partners in the Marcellus Shale, and ACP III Utica LLC (“ACP III”), both affiliates of Avista Capital Partners, LP, a private equity fund (collectively with ACP II and ACP III, “Avista”). During the term of the Avista Utica joint venture, the joint venture partners acquired and sold acreage and we exercised options under the Avista Utica joint venture agreements to acquire acreage from Avista. The Avista Utica joint venture agreements were terminated on October 31, 2013 in connection with our purchase of certain ACP III assets discussed below. In October 2012, the Company sold substantially all of its interests in oil and gas properties dedicated to the Avista Utica joint venture in the northern portion of the Utica play to an unrelated third party. Simultaneously with the closing of this Utica transaction, Avista sold substantially all of its interests in the same oil and gas properties. In connection with these sale transactions, the Company elected to exercise its option to increase its participating interest in the same oil and gas properties on a “net proceeds basis” so that the Company received net proceeds with respect to 50% of the properties subject to the sale rather than the 10% the Company initially held. Pursuant to the terms of the Avista Utica joint venture agreement, as amended, the Company paid $24.0 million for the 40% additional interest in the acreage subject to the sale and certain other Avista Utica joint venture properties. Therefore, effective as of the closing, both parties owned the joint venture properties equally and both parties shared equally in their right to receive the proceeds from the purchaser. As a result of the reduction required for the $24.0 million option exercise price due from the Company and the repayment of other amounts owed between the two joint venture parties, the net proceeds received by the Company from the sale was $51.7 million and the net proceeds received by Avista from the sale was $74.9 million. Concurrently with the exercise and closing of the Company’s option to increase its participating interest in such oil and gas properties, its right to receive distributions associated with properties owned by ACP II in the Avista Utica joint venture through “B Units” interest in ACP II was terminated. Following the sale transactions described above, on October 24, 2012, the Company and Avista amended the Avista Utica joint venture agreements to provide that the expiration date of the Company’s remaining option to increase its participating interest in the Avista Utica joint venture properties was accelerated from March 2013 to January 15, 2013. The Company exercised this option on January 15, 2013 by paying $63.1 million for an additional 40% in the remaining Avista Utica joint venture properties. The Company and Avista also agreed that after the option was exercised, the Company’s participating interest in subsequently acquired properties within the then existing area of mutual interest continued to be 10% and Avista’s participating interest continued to be 90%, and the Company was granted an additional option to increase its 10% ownership in such subsequently acquired properties to 50% at 8.625% above acreage cost and associated improvements (compounded monthly following Avista’s contribution of purchase proceeds). Instead of exercising this option, the Company and Avista agreed that the Company could instead elect to acquire additional properties on an equal basis with Avista. In connection with the January 2013 exercise of the Company’s option to increase its participating interest in the Avista Utica joint venture properties, its right to receive distributions associated with properties owned by ACP III through “B Units” interest in ACP III that the Company acquired at the formation of the Utica joint venture was terminated. On October 31, 2013, the Company completed the acquisition of acreage located primarily in Guernsey and Noble counties, Ohio from Avista. This transaction had an effective date of July 1, 2013, and the Company paid Avista approximately $78.6 million in cash, subject to post-closing adjustments. Prior to the Company’s acquisition from ACP III, the properties in the Avista Utica joint venture were held on an equal basis by the Company and Avista. This transaction was initially funded with proceeds from the sale of the Company’s remaining oil and gas properties in the Barnett to EnerVest. After giving effect to this transaction, the Company and Avista remain working interest partners in Utica with the Company acting as the operator of the jointly owned properties which are now subject to standard joint operating agreements. The joint operating agreement with Avista provide for limited areas of mutual interest around properties jointly owned by the Company and Avista. Avista Marcellus Joint Venture. Effective August 2008, Carrizo (Marcellus) LLC, a wholly owned subsidiary of the Company, entered into a joint venture arrangement with ACP II, an affiliate of Avista. In September 2010, the Company completed the sale of 20% of its interests in substantially all of its oil and gas properties in Pennsylvania that had been subject to the Avista joint venture to Reliance. Simultaneously with the closing of this transaction, ACP II closed the sale of its entire interest in the same properties to Reliance for a purchase price of approximately $327.0 million. At the time of entering into the agreements for these transactions, the Company and Avista agreed that B Unit distributions to the Company with respect to Avista’s sale of properties to Reliance would be principally based upon Avista’s internal rates-of-return and return-on-investment thresholds associated with such properties, subject to amounts withheld from distribution by ACP II’s board. In connection with these sales transactions, the Company and Avista amended the participation agreement and other joint venture agreements with Avista to provide that the properties that the Company and Avista sold to Reliance, as well as the properties the Company committed to the new joint venture with Reliance, were no longer subject to the terms of the Avista Marcellus joint venture, and that the Avista Marcellus joint venture’s area of mutual interest would generally not include Pennsylvania, the state in which those properties were located. The Company’s joint venture with Avista continues, primarily in New York and West Virginia. Pursuant to the terms of the amended participation agreement, the areas of mutual interest with Avista have been reduced to specified halos around existing properties in New York and West Virginia. On November 16, 2010, Carrizo Marcellus assigned, via distribution and subsequent contribution, its interests in the Avista Marcellus joint venture to Carrizo (Marcellus) WV LLC (“Carrizo WV”), also a wholly owned subsidiary of the Company. In connection with the assignment, Carrizo Marcellus assigned to Carrizo WV its rights and obligations under the participation agreement, as well as the related joint operating agreement, pursuant to which operatorship of the Avista Marcellus joint venture was assumed by Carrizo WV. In addition, Carrizo WV and the other parties thereto amended and restated the participation agreement on November 16, 2010, effective as of October 1, 2010. This amended and restated participation agreement amends the participation agreement by, among other things, (i) providing fixed percentages and thresholds for sharing net cash flow from hydrocarbon production and proceeds from the sales of underlying joint venture properties and (ii) eliminating provisions that have been performed and are inapplicable going forward. The Company serves as operator of the properties covered by the Avista Marcellus joint venture under a joint operating agreement with Avista and also performs specified management services for ACP II. An operating committee composed of one representative of each party provides overall supervision and direction of joint operations. Avista or its designee has the right to become a co-operator of the properties if all of its membership interests or substantially all of its assets are sold to an unaffiliated third party or if the Company defaults under the terms of any pledge of its interest in the properties. Each party now has ability to transfer its interest in the Avista Marcellus joint venture to third parties subject in most instances to preferential purchase rights for transfers of less than 10% of a party’s interest in joint venture properties, and to “tag along” rights for most other transfers. Carrizo Relationship with Avista. Steven A. Webster, Chairman of the Company’s Board of Directors, serves as Co-Managing Partner and President of Avista Capital Holdings, LP, which entity has the ability to control Avista and its affiliates. As previously disclosed, the Company has been and is a party to prior arrangements with affiliates of Avista Capital Holdings LP. The terms of the joint ventures with Avista in the Utica and the Marcellus as well as the Avista Transaction and the other acquisition transactions described above with Avista were each separately approved by a special committee of the Company’s independent directors. In determining whether to approve or disapprove a transaction, such special committee has in the Avista Transaction and generally in other transactions since the beginning of the last fiscal year, determined whether the transaction is desirable and in the best interest of the Company. In transactions prior to the recent Avista Transaction, the special committee has evaluated whether transactions are fair to the Company and its shareholders on the same basis as comparable arm’s length transactions. The committee has applied in the Avista Transaction, and may in other transactions also apply, standards under relevant debt agreements if required. Advances to and from Avista and Affiliates. At December 31, 2013, related party receivable and related party payable on the consolidated balance sheets included $6.6 million and $2.8 million, respectively, representing the net amount ACP II owes the Company related to activity within the Avista Marcellus joint venture and the net amount the Company owes ACP III related to activity within the Avista Utica joint venture, respectively. At December 31, 2012, related party receivable on the consolidated balance sheets included $9.8 million, representing the net amounts ACP II and ACP III owed the Company related to activity within the Avista Marcellus and Avista Utica joint ventures.

10. Related Party Transactions

Avista Utica Joint Venture. Effective September 2011, the Company’s wholly-owned subsidiary, Carrizo (Utica) LLC, entered into a joint venture in the Utica Shale with ACP II Marcellus LLC (“ACP II”), which is also one of our joint venture partners in the Marcellus Shale, and ACP III Utica LLC (“ACP III”), both affiliates of Avista Capital Partners, LP, a private equity fund (collectively with ACP II and ACP III, “Avista”). During the term of the Avista Utica joint venture, the joint venture partners acquired and sold acreage and we exercised options under the Avista Utica joint venture agreements to acquire acreage from Avista. The Avista Utica joint venture agreements were terminated on October 31, 2013 in connection with our purchase of certain ACP III assets discussed below.

In October 2012, the Company sold substantially all of its interests in oil and gas properties dedicated to the Avista Utica joint venture in the northern portion of the Utica play to an unrelated third party. Simultaneously with the closing of this Utica transaction, Avista sold substantially all of its interests in the same oil and gas properties. In connection with these sale transactions, the Company elected to exercise its option to increase its participating interest in the same oil and gas properties on a “net proceeds basis” so that the Company received net proceeds with respect to 50% of the properties subject to the sale rather than the 10% the Company initially held. Pursuant to the terms of the Avista Utica joint venture agreement, as amended, the Company paid $24.0 million for the 40% additional interest in the acreage subject to the sale and certain other Avista Utica joint venture properties. Therefore, effective as of the closing, both parties owned the joint venture properties equally and both parties shared equally in their right to receive the proceeds from the purchaser. As a result of the reduction required for the $24.0 million option exercise price due from the Company and the repayment of other amounts owed between the two joint venture parties, the net proceeds received by the Company from the sale was $51.7 million and the net proceeds received by Avista from the sale was $74.9 million. Concurrently with the exercise and closing of the Company’s option to increase its participating interest in such oil and gas properties, its right to receive distributions associated with properties owned by ACP II in the Avista Utica joint venture through “B Units” interest in ACP II was terminated.

Following the sale transactions described above, on October 24, 2012, the Company and Avista amended the Avista Utica joint venture agreements to provide that the expiration date of the Company’s remaining option to increase its participating interest in the Avista Utica joint venture properties was accelerated from March 2013 to January 15, 2013. The Company exercised this option on January 15, 2013 by paying $63.1 million for an additional 40% in the remaining Avista Utica joint venture properties. The Company and Avista also agreed that after the option was exercised, the Company’s participating interest in subsequently acquired properties within the then existing area of mutual interest continued to be 10% and Avista’s participating interest continued to be 90%, and the Company was granted an additional option to increase its 10% ownership in such subsequently acquired properties to 50% at 8.625% above acreage cost and associated improvements (compounded monthly following Avista’s contribution of purchase proceeds). Instead of exercising this option, the Company and Avista agreed that the Company could instead elect to acquire additional properties on an equal basis with Avista. In connection with the January 2013 exercise of the Company’s option to increase its participating interest in the Avista Utica joint venture properties, its right to receive distributions associated with properties owned by ACP III through “B Units” interest in ACP III that the Company acquired at the formation of the Utica joint venture was terminated.

On October 31, 2013, the Company completed the acquisition of acreage located primarily in Guernsey and Noble counties, Ohio from Avista. This transaction had an effective date of July 1, 2013, and the Company paid Avista approximately $78.6 million in cash, subject to post-closing adjustments. Prior to the Company’s acquisition from ACP III, the properties in the Avista Utica joint venture were held on an equal basis by the Company and Avista. This transaction was initially funded with proceeds from the sale of the Company’s remaining oil and gas properties in the Barnett to EnerVest. After giving effect to this transaction, the Company and Avista remain working interest partners in Utica with the Company acting as the operator of the jointly owned properties which are now subject to standard joint operating agreements. The joint operating agreement with Avista provide for limited areas of mutual interest around properties jointly owned by the Company and Avista.

Avista Marcellus Joint Venture. Effective August 2008, Carrizo (Marcellus) LLC, a wholly owned subsidiary of the Company, entered into a joint venture arrangement with ACP II, an affiliate of Avista. In September 2010, the Company completed the sale of 20% of its interests in substantially all of its oil and gas properties in Pennsylvania that had been subject to the Avista joint venture to Reliance. Simultaneously with the closing of this transaction, ACP II closed the sale of its entire interest in the same properties to Reliance for a purchase price of approximately $327.0 million. At the time of entering into the agreements for these transactions, the Company and Avista agreed that B Unit distributions to the Company with respect to Avista’s sale of properties to Reliance would be principally based upon Avista’s internal rates-of-return and return-on-investment thresholds associated with such properties, subject to amounts withheld from distribution by ACP II’s board. In connection with these sales transactions, the Company and Avista amended the participation agreement and other joint venture agreements with Avista to provide that the properties that the Company and Avista sold to Reliance, as well as the properties the Company committed to the new joint venture with Reliance, were no longer subject to the terms of the Avista Marcellus joint venture, and that the Avista Marcellus joint venture’s area of mutual interest would generally not include Pennsylvania, the state in which those properties were located. The Company’s joint venture with Avista continues, primarily in New York and West Virginia. Pursuant to the terms of the amended participation agreement, the areas of mutual interest with Avista have been reduced to specified halos around existing properties in New York and West Virginia.

On November 16, 2010, Carrizo Marcellus assigned, via distribution and subsequent contribution, its interests in the Avista Marcellus joint venture to Carrizo (Marcellus) WV LLC (“Carrizo WV”), also a wholly owned subsidiary of the Company. In connection with the assignment, Carrizo Marcellus assigned to Carrizo WV its rights and obligations under the participation agreement, as well as the related joint operating agreement, pursuant to which operatorship of the Avista Marcellus joint venture was assumed by Carrizo WV. In addition, Carrizo WV and the other parties thereto amended and restated the participation agreement on November 16, 2010, effective as of October 1, 2010. This amended and restated participation agreement amends the participation agreement by, among other things, (i) providing fixed percentages and thresholds for sharing net cash flow from hydrocarbon production and proceeds from the sales of underlying joint venture properties and (ii) eliminating provisions that have been performed and are inapplicable going forward.

The Company serves as operator of the properties covered by the Avista Marcellus joint venture under a joint operating agreement with Avista and also performs specified management services for ACP II. An operating committee composed of one representative of each party provides overall supervision and direction of joint operations. Avista or its designee has the right to become a co-operator of the properties if all of its membership interests or substantially all of its assets are sold to an unaffiliated third party or if the Company defaults under the terms of any pledge of its interest in the properties.

Each party now has ability to transfer its interest in the Avista Marcellus joint venture to third parties subject in most instances to preferential purchase rights for transfers of less than 10% of a party’s interest in joint venture properties, and to “tag along” rights for most other transfers.

Carrizo Relationship with Avista. Steven A. Webster, Chairman of the Company’s Board of Directors, serves as Co-Managing Partner and President of Avista Capital Holdings, LP, which entity has the ability to control Avista and its affiliates. As previously disclosed, the Company has been and is a party to prior arrangements with affiliates of Avista Capital Holdings LP.

The terms of the joint ventures with Avista in the Utica and the Marcellus as well as the Avista Transaction and the other acquisition transactions described above with Avista were each separately approved by a special committee of the Company’s independent directors. In determining whether to approve or disapprove a transaction, such special committee has in the Avista Transaction and generally in other transactions since the beginning of the last fiscal year, determined whether the transaction is desirable and in the best interest of the Company. In transactions prior to the recent Avista Transaction, the special committee has evaluated whether transactions are fair to the Company and its shareholders on the same basis as comparable arm’s length transactions. The committee has applied in the Avista Transaction, and may in other transactions also apply, standards under relevant debt agreements if required.

Advances to and from Avista and Affiliates. At December 31, 2013, related party receivable and related party payable on the consolidated balance sheets included $6.6 million and $2.8 million, respectively, representing the net amount ACP II owes the Company related to activity within the Avista Marcellus joint venture and the net amount the Company owes ACP III related to activity within the Avista Utica joint venture, respectively. At December 31, 2012, related party receivable on the consolidated balance sheets included $9.8 million, representing the net amounts ACP II and ACP III owed the Company related to activity within the Avista Marcellus and Avista Utica joint ventures.